I think Magnus has an advantage because he will likely win the rapid tiebreak but I wouldnt be surprised to see Caruana nick a game and win it all. Its clear that those who were predicting the match beforehand were simply pressing random buttons and throwing narratives around.
But that's nothing new. We had that guy in the other thread unironically proclaiming that Carlsen would have draw odds in the match. Some people were assigning him an 80% chance to retain his title.
Was he a favourite? Sure he was, but not nearly by as much as people proclaimed. It may or may not have increased a bit, now that a significant portion of Caruana's prep has maybe or not gone down the toilet due to the inability of the St. Louis Chess Club people to not have their heads up their asses all the time. That's difficult to asses from afar, though, and only Team Caruana knows the exact impact their own sponsors shooting them in the foot had on the match.
I think he might be close to 80%. It all depends on how high a draw % you assign to each game. If it's 70%+ draw chance I remember being surprised at how large a favorite he is simply due to tiebreaks being quite likely.
Also, I do not think a "significant" portion of prep went down the toilet and it shouldn't be too difficult to assess from afar.
Perhaps that one interesting line that Hammer is trying to research (although if an almost super GM is crowd sourcing to try and figure out what line is being referred to it doesn't necessarily seem very helpful) is revealed and that was a "big surprise" Fabi had for Carlsen in the Petroff.
However, of the other lines shown, Carlsen's team already knows Fabiano almost surely has the Petroff deeply analyzed and also the QGD based on Fabi's surprise in that opening already. In fact, the line in the QGD that took Carlsen off-guard isn't even shown on the screen but the main line instead.
My guess is the only real way this can affect Caruana's team is if it simply unbalances them from the viewpoint of "our sponsor leaked something they shouldn't have." In terms of prep it could even help. Fabi likely has a bunch of stuff in the Petroff prepared and Magnus has already lost some of his chances to test it so even if he decides to throw away the one interesting line he likely has several others to play.
Fabi pushing with black. If he can actually manage to convert, this would be the best thing for the match that can happen before the rest day and Carlsen's second White in a row.