Squad depth and experience tend to give Barcelona an edge over Napoli in the Champions League, but the teams' performances this season have been relatively similar in their respective domestic leagues. I hope that Barcelona will be able to qualify for the quarter-finals this season by beating Napoli, even if Barcelona fails to reach the semi-finals then Xavi will actually have brought the team up two levels from previous seasons in the Champions League. Of course I don't consider Barcelona capable of getting to the final and winning the title, that seems unlikely.
Napoli was the home team in the first leg, so it is possible that they could perform better than Barcelona. I don't think we can analyze what their chances will be in this match, I mean there are several things that might change it, including the availability of players in the starting line-up.
I doubt if Barcelona will be able to defeat Napoli easily; remember, Barcelona is not in a good form this season, they couldn't make it in the Champions League last season, and some of their players were injured; while Napoli is not also too strong this season due to injury, they are in good shape than Barcelona because they have players to depend on, and with the way they played in the Champions League last season, I think this Xavi's team cannot easily defeat Napoli, but it will not be easy to predict because all the teams can qualify.