With only 2 points more than Inter Milan but with less goal difference, Napoli does not have too big advantage against Inter Milan for winning Scudetto. If Napoli lose one match, they can fall behind Inter Milan instantly, it's big risk for Napoli. Napolli are not too strong for winning all last 13 matches and Inter Milan will have some opportunities for catching and passing through Napoli in Serie A.
The opportunity is the same because even though Napoli is not strong enough to compete, they are quite fortunate because they can focus more on finishing the season in a more consistent way, while Inter Milan has a busier schedule because they are still playing in the Champions League so in my opinion Napoli is much more favored even though it really depends on how they can perform consistently in the remaining matches for this season.
The remaining 13 matches must be really utilized well by Napoli and they must not lose if they want to get the Scudetto. Of course it is not easy because Inter Milan themselves will also fight to win the title and even though they have a tight schedule, Napoli themselves must be aware.