One thing you can do when you don't know the fighters is to try to read the tone of the chat. Quite often you can tell if it's an uneven match (and which way it leans) by how people talk. It's not completely reliable of course, but one of the biggest tells is if a bunch of people start spamming "always/never bet DBZ/waifu/MSpaint/tits/etc." or fake/real, especially with iterations of Ryu and Akuma.
Heh. For every time that's true, I've seen it be false. It depends on how well that chat's doing at trolling at that particular moment* or the general mood. Better is probably to track the few people that actually give consistently good advice and listen to them, at least if you're going the chat oracle route. Personally, I generally consider the chat to be inherently unreliable noise when it comes to who to bet on. Chat's there for other reasons
*Because remember, a significant amount of them are trying to get other people to bet on whoever they're
not betting on, and there's at least a notable minority of them that are just as good or better at playing mind games than you are at reading them.
E: On the other hand, it can be pretty great to see the chat's response when you actually know what's about to happen with a match, especially if it's one that is, or at least
looks, close. That can be wonderful :3