Re: Autocracy and Culture Victory:
Just to clarify, Futurism is quite a small bonus indeed for Culture Autocracy, as +100 Tourism (even per civ, rather than in total) normally only the equivalent of two to ten turns of culture pressure, depending on how high you push your normal output.
The really big boost comes from Cult of Personality, as those % bonuses stack. They key here is being very careful how you set up the wars, and carrying out several wars in parallel.
Say you have France and Brazil pumping out a mass of culture, and you have four other nations you're already close to Dominant with. If you can pay France and Brazil to fo to war with those four other nations, you can then declare war on those same four nations, and get +200% Tourism for at least 10 turns, and probably longer. Thats a lot bigger bonus than Futurism.
Re: Autocracy and Science:
You can't buy Spaceship Parts with Gold like Freedom can, and you can't Great Engineer them like Order can. This does slow you down a little.
Actually though, the main factor in Science Victories is getting the tech lead first, and Autocracy can be good at Science because:
1) It is the best Happiness generating ideology. Happiness = more growth and more population = more science.
2) Its the best Ideology for keeping a huge army. Huge army = control over when you go to war (i.e. you DoW on others, not them on you) = easier to build and move spaceship parts without panicking about surprise backstab attacks on you.
3) Its the best Ideology for making war from a tech disadvantage. This means you can focus on space tech without losing all the wars you have to fight, and can use spies to steal techs along paths you're not focusing on.
4) Its the best Ideology for kicking ass. This means that if someone else is getting close to their victory condition and will reach it before you finish your spaceship, you can go smack them down.
Thats not to say Autocracy is the BEST ideology for science victory, just that it is isn't completely lacking in advantages that serve that victory goal.