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.
Not having a really brilliant performance at the champions League has been a trend for PSG in the past seasons, they just only get to have regular appearance because they have that unwavering dominance in their domestic league which gives them the edge to continually have an appearance in the champions League. Underestimating Salzburg will be an error on the side of PSG because even PSG isn't sure they are going to be able to win them without a fight, although the chances are high that PSG will win but how easy will that come or maybe we should anticipate a draw.