Any victory option is possible in any game. For balance, juct go middle-of-the-road in all choices.
The smarter the AI, the less likely anyone is to manage any victory quickly. Tech victory is easier when research is faster. Influence victory is easier when stars are spread out, since it depends on the sheer area your influence covers, not how focused it is. Most other universe options aren't that major in suggesting a victory path.
The AI choices are very important for determining whether a conquest victory or an alliance victory is likely. The conquest/alliance balance comes from the ethics of the races that wind up in the galaxy. If they're mostly evil, expect a war heavy game. If they're mostly good, expect a treaties screen full of blue lines. Either way, expect a fair quantity of fighting between opposite alignments.
Any way you set it up, keep in mind that the AI doesn't consider you to be "the human player". You're just another civilization, and like any other, are unknown in intent. You can identify some of the end conditions that the AIs want (Terrans try for Alliance, Dengrin go for Conquest), but they're not mindlessly fixated on them. That's a big part of why I find GC to be so much fun- it's inherently unpredictable.
