The Napoli vs Inter match will not be a match that will elect the winner of Serie A but it could give an important clue as to who could win it.
Currently, only one point of difference is easily recoverable, assuming an Inter victory it would become 4 but it will not be a sure advantage until the end of the championship. If Napoli wins, Inter would find themselves at -2 again, and in any case it is not an insurmountable advantage.
Whoever wins tomorrow doesn't give much of a clue as to who's going win the league. There are 12 more matches to go and anything can happen. Looking at the top leagues in europe, the way the table is right now, you can easily predict who's going to win the league but the Italian seria a is the exception. The differences between the teams are not much and they've been displacing and over taking each which makes it very interesting. Inter, Napoli and Atalanta are all in the title race and maybe we're going to wait till matchday 38 for us to know who's going to be the winner.
This is Italian league anything can happen down to the last match of the season so this match might give wrong clue on who the potential winner of this season's league is going to be. Atlanta is still in the title race contenders, their last five matches looks more appealing than that of Napoli who haven't won a single match in their last five games.
With the eleven games left to end the season it will take the most determined and consistent to lift the trophy. Before now seria A competitions were very difficult to predict because then the contention used to be between Inter, Milan and Juventus. But when Napoli got into the picture the competitions slagged a bit.