I think that Barcelona just now look a bit worse than Napoli in terms of their physicality, so you can make even a slight bias in favour of a Napoli win. But since there will be two matches, it's hard to say exactly how the 1/8 will end. Both teams know how to get back on track
Do you mean many of Barcelona players injured?
Indeed, Barcelona still has 4 injured players. There are Iñigo Martínez, Marcos Alonso, Pedri, Gavi, and Ter Stegen. Losing these players will bring big impacts for Barcelona performance. Specifically losing the main goalkeeper, Ter Stegen.
Meanwhile, Napoli only has 2 injured players, both of them are not the main players. So, Napoli has no problem with injured players.