I don't see any way Marseille are catching up with them from now on. Because they aren't even consistent these days. After losing to PSG home this time they got a draw against Strasbourg home. Balerdi's incident just finished them. Strasbourg aren't even one of the decent teams in the league this season. They are trying to hold onto the Ligue 1 not to relegate. Marseille need to play more carefully in such games to finish them without point loss.
Paris Saint Germain got lots of superstar payers and much more investments compared to the other teams so I guess for the other teams like Marseille and Monaco it's difficult to get close to them, however after they lost in the champions league, Neymar got injured and Messi going to leave, PSG's atmosphere is not good like the other days and I guess there is a chance for them to lose some points during the games they are going to have.