Both tourism and culture are factored in. Read the guide on culture victory if you need more details on how the influence level are defined. Ideological pressure is related on the difference on influence levels.
http://www.carlsguides.com/strategy/civilization5/culturalvictory.php
Unknown 0%, Exotic 10%, Familiar 30%, Popular 60%, Influential 100%, Dominant 200%
For example, if your civ is Popular over civ X, but X is Exotic over you, then overall you have 2 levels of influence over X. Another example, if your civ is Exotic over Y, but Y is Influential over you, then Y has 3 levels of influence over you.
Now you can check the Cultural Victory tab of the Cultural Overview screen. If you mouse over the entries under Public Opinion, they show levels of influence over civs have over you.
Now sum the levels of influence of a different ideology D, and sum the levels of influence of the same ideology with you S. If world ideology is passed, then its corresponding ideology has 2 additional levels. Now calculate the value D-S.
Public opinion will be Content if the value is less than 2, Dissident if it's 2 or 3, Civil Resistance if it's 4 or 5, Revolutionary wave if it's at least 6.