PSG's performance this season is not very good in the Champions League, but they have quality players compared to Salzburg. The chances of winning should be better than the home team, but we should not underestimate Salzburg who is playing at home. The worst result I can think of for the match is a draw, but the probability of PSG winning would probably be high.
This will be a difficult situation for PSG because looking at the remaining matches, the opponents they will face and their current position are really not profitable for them.
Now there are only 3 more matches left for them and the opponents they will face are not easy opponents. In terms of condition and experience compared to Salzburg and VfB who will be their opponents in the remaining matches, PSG may still be superior but the problem is they also have to face Manchester City in the Champions League which is likely to lose their points in this match.
So in order to qualify, the target of winning against Salzburg and VfB must be PSG's initial benchmark now because in any case this can boost their position, even though it is difficult, for the match against Salzburg they must be able to get full points in order to maintain their hopes of staying on the play-off path.