With the way PSG performed in the group stage of the Uefa Champions League, I do not expect PSG to progress to the quarter-final of the Uefa Champions League this season, but PSG had an easy draw in the round of 16 against Real Sociedad, and they will win against Real Sociedad to reach the quarter-final of the Uefa Champions League.
Since PSG will play against Real Sociedad, I'm very sure that they will have a good chance to qualify for the next round. It is true that PSG didn't play consistently during this season, they sometimes got surprising defeats or draws. However, I believe PSG has much better quality squad over Real Sociedad. PSG still have some stars players in their squad, they have a special advantage in the match against Real Sociedad.
Barcelona faced with crucial problem injury because many of key player have been absent until the end of this season and they will absent on Champion League match phase of 16. Gavi, and Ter Stegen is the most important players for Barcelona who filled line up on every match, but loss him exactly with Ter Stegen Barcelona have conceded many goals last several matches and this proof how important him for Barcelona goal keeper.
Yes. Barcelona is facing a problem with the injury. However, I'm sure Xavi can deal with the current injured players. They still have enough players to beat Napoli. As long as Barcelona has enough attackers, they will have the chance to win the match. They have enough midfielders and they have some options for defenders. They only have very limited option for goalkeeper and attackers.