Unless you are proposing to make the victory paths identical, they will differ either in how fast they can be accomplished, how difficult their goals are, and how much other civs can interfere with you.
- Domination:
- The fastest victory
- Potentially winnable in any era as fast as you can beat everyone on the map.
- Very difficult to achieve, essentially having to conquer every other player in an 8-way free-for-all
- Easy for other civs to resist simply by defending themselves against you.
- Domination also doubles as the most effective and obvious way of disrupting someone else's victory path.
- Carries a high cost as you are perceived by other civs as dangerous, and that dealing with you isn't profitable.
- Potentially impossible to achieve - If a military stalemate happens, its very possible you just wouldn't be able to kill everyone in time.
- Cultural:
- An early victory type.
- Requires high investment in culture to have the requisite policies, but the tech prerequisites are early.
- Requires large investments in dedicated tourism infrastructure, which is costly and of limited value outside this victory path
- Like Domination, requires you to overwhelm other civilizations' defenses
- Unlike Domination, the defeat is indirect and reversible, but it is harder for other civs to resist directly.
- Other civs can counter it by bolstering their own culture and investing in infrastructure that will resist foreign influence.
- Potentially impossible to achieve. Another civ could make more cultural defense than you could ever match with tourism offense, stalling a CV indefinitely.
- Diplomatic:
- Somewhat late and slow.
- Has a late tech lock, but only 1.
- Fairly self-contained. Requires a lot of interaction with minor players (ie. city-states), but not necessarily major players.
- Reversible, with strong WC proposals (eg. decolonization) and enemy counterplay options (eg. outcompeting or killing City-states)
- Potentially Inevitable. Every failed world leader vote gives, more free WC votes to the Diplo leader. They will get enough votes eventually unless another victory happens.
- Science:
- Very late, slow victory
- Is basically entirely composed of tech locks and a Production gate.
- Progress is irreversible and virtually impossible for other players to interfere with short of killing you.
- Almost inevitable. The only thing preventing it is a Time Victory happening first
- Time:
- The latest, slowest victory
- Inevitable and cannot be stopped.
Those are the basic outlines of the victories. People think that CV is too common. That's not necessarily true, there is no requirement that all VCs be treated equally, but too many of 1 victory makes that VC feel more viable than others, and makes games feel more similar.
Here are the levers you could pull for CV:
- Push later by adding later tech prerequisites
- My least favorite solution. Culture already has a minimum policy prerequisite so this is repetitive.
- Diplo victory already has the main constraint of 1 super-late game tech unlock. How about we not make these identical?
- If anything I would suggest that we take the tech prerequisite out entirely. Adding tech prerequisites is homogenizing the victories and going in the opposite direction
- Push later by increasing the policy prerequisites
- I'm not entirely opposed to this suggestion, but it's lazy and unimaginative.
- It doesn't really engage with the game mechanics other than to make a number bigger.
- I would instead propose that policies and tenets cost more overall, rather than simply increasing the number required
- Decrease the overall sources of
cultural offense and strengthen the sources of 
cultural defense
- This is the proposal that directly engages with the nuts & bolts of the game mechanics
- Any strengthening of cultural defense will make policy adoption faster; a proposal that adds to defense should also look at increasing policy costs to prevent knock-on effects
- Make the victory riskier by removing late game steroids
- Involves weakening or removing powerful endgame tools like T3 tenets, buildings, wonders, and tech modifiers
- Make stalling a cultural leader more viable, forcing them to kill cultural holdouts, switch to another victory path, or lose.
- The current CV is faster than DiploV, but also feels less risky. Stalling a CV with cultural resistance is harder than killing or flipping CS allies.
- This will make CV more different from SV and DiploV by making the victory path feel more frontloaded and less inevitable.
- Raise the opportunity cost of Tourism sources, thereby making them riskier and less attractive to develop everywhere
- Make cultural infrastructure more niche by weakening the number of bonuses they give individually, and increasing the overall
cost and 
maintenance on your empire
- Find more ways to dislocate infrastructure from infrastructure, making cultural buildings easier to justify and incorporate into your build queues while sources remain firmly niche
- The Hotel is the arch example of this: Only gives , and has a relatively high and burden
- A late game source of from tiles would also be a good idea, because tiles engender an opportunity cost every turn by locking finite tiles around a city and
population that could be used for other things.
TL;DR - Cultural victory is comparatively fast and easy to stop. If you want fewer of them you can either make them slower or even easier to stop. I support making them easier to stop.
