Injuries might not be a serious problem for PSG as it might be for Bayern Munich. PSG have really good squad depth when it comes to attacking options as they have Mbappe, Lionel Messi, Neymar, Draxler, and Angel di Maria in their squad. This means that the coach can rotate the squad even if one or two players are missing.
PSG have many better players than Bayern Munich but in many seasons we saw PSG got troubles when one or two key players missed one match in knock-out phase of Champions League. Moreover they failed too even with their best players and I believe that if PSG have some injured players by World Cup 2022, they will lose a lot of strength when Champions League returns. With burden of failed past seasons, they might be beaten by Bayern Munich.
Currently, both teams are level in quality and performance which is main point but what will be happened after two months it's still not predictable because things can change in any match with new injury or any other issue specially while we have January transfer window where many players will try to leave for the better future and as we all know Neuer is also out for Bayern Munich which is surely a big setback for them but still we have to wait for the updates Neymar is back and now doing his stuff for the preparation after the break and Messi and Mbappé are still in Qatar with their national teams.
With both teams are having good command in their domestic leagues we can expect good fight in Champions League even injuries and other things are still happening and can create problems for the both teams but still any team can win and go into quarterfinal of the Champions League.