Inter don't have a very big gap in the standings... Don't forget that Napoli and Atalanta have no matches in the UCL... It's a very big pressure for Inter if they want to beat Bayern or get to the UCL final... But if they make a mistake, Napoli or Atalanta will definitely take that chance to take the lead... It seems to me that in Serie A it is not yet certain who can become the leader...
In theory...
In reality Atalanta had just one match to consider, the one against Inter, it lost!
Napoli also had nothing else on its plate, it drew with Venezia.
So while theoretically, Inter was under pressure the most it's the only team at the top that did nothing the last two weeks while it was the competitors that did the mistakes and lost precious points. Furthermore, Inter is dealing with Udinese, Parma and Cagliari next, Napoli is facing Bologna and Milan, while Atalanta has Fiorentina and Lazio, that's a serious difference.