I didn't think PSG can beat Manchester City even in their current state. Manchester City are not in a comfortable place in the standing and a win over PSG will be very important for them because it will significantly improve their standings and taking them from 22nd on the standings to 15th. This is a must win match for both teams but I think Manchester City will have a slight advantage over PSG.
Looking at the condition of both teams, of course PSG is much more favored to win the match because so far they have been quite consistent in Ligue 1 and the match will also take place at PSG's home ground. But looking at their performance in the Champions League, maybe this is a little different and there is a possibility that PSG will face a fairly difficult match when facing Man City and to get the win they must perform better by taking advantage of the home game.
Man City themselves also need a win in order to qualify through the playoffs because their current position is quite risky and they are not certain they can qualify if they lose to PSG. This will be a very important match for both teams because both will determine their steps in the next round.
Even if PSG wins, PSG will not go up to 15th place, Lol. After all, if PSG wins then PSG has 10 points and at the moment, there are several teams with 10 points and also with good goal aggressiveness such as Benfica, Monaco and Sporting, at least PSG must win with a gap of three to four goals if they want to go up for that position. Moreover, these teams are also at least not certain to lose, so even if PSG wins and at the same time these teams also win at least PSG only has a chance to enter the top 24 but not go up to 15th place.
But yes, apart from that, basically Manchester City is also not a completely weak team even though it is still in a negative trend so far this season. Thus, there will still always be a chance for Manchester City to successfully stay in the top 24 although indeed, of course, this match will still be a difficult match for PSG and Manchester City, because they both still desperately need points.