so far I am not saying that Napoli is a bad team, it's just that the two teams between Barcelona and Napoli have differences and the first difference is that Barcelona experience in the UCL is very big compared to Napoli so Barcelona chances of success in the UCL are superior to Napoli.
however, in terms of players, Napoli has the advantage because in terms of finances Napoli is also better than Barcelona and in this difference I cannot compare which team is strong and which team is bad because both teams have their own advantages and disadvantages.
from my own opinion Barcelona chances of qualifying for the next match are very slim and even Napoli also has a very small chance because as I said above they both have their own advantages but if it is just speculation if Napoli in the 1st match can win more scores because they are playing at home. most likely in the second match, Napoli can qualify because Napoli only needs a few scores to be ahead of the aggregate they have.
but the problem is that Barcelona won't let that happen because I'm sure if Xavi is very smart and knows what he has to do then a draw in the 1st match could possibly happen.
Yes to every advantage there’s always one major disadvantage and we can see that in the strengths ad weaknesses of these teams to play each other in the UCL Round of 16. Napoli this season are of the average and we can say almost same for Barcelona especially as they lost most of their players due to injury, which has caused their major problems lately.
Now for this fixture, I think I’ll give Napoli the upper hands because they’re one team that have the determination. Yes, Barcelona have the experience but not with most of these their current squad. For this fixture, I think the major fare will be decided from the very first leg and who defends pretty well and for that I see Napoli going through because of some errors the Barcelona defense has made this season already, coupled with lack of creativity in their final third lately.