The main factor is because Napoli got 2 red cards, while Fiorentina only got 1 red card. But apart from that, Fiorentina played with discipline after only playing with 10 players, then Napoli became frustrated until they couldn't do much and conceded again in extra time. Furthermore, Fiorentina will play against Atalanta in the quarter-finals, Atalanta is not an easy opponent because when compared to Napoli today I still think Atalanta is still the best because Napoli themselves continue to decline and that is very worrying.
I fully agree with your analysis of the match.
Naples very ugly to see, very nervous. Being nervous doesn't help you stay focused.
Regarding Atalanta, they are a very tough opponent, I see them very badly. In my opinion,
Atalanta wins, having reserves to take from their spring legion.