Paris Saint German never gave Marseille the privilege to close the gap because they kept on winning more matches and that made PSG less concerned about the League games while they're doing well and focusing in the Champions League games.
However, PSG have not lost this season and they have maintained the points gap quite well with Marseille. They do not need to worry too much about Marseille because PSG can still play well in Ligue 1. No team will chase their points at this time. Now let other teams like Monaco, Nice, and Marseille compete for the standings below PSG.
PSG is very ambitious for the Champions League, this season they got a good opportunity in the Quarter-finals and must try to advance to the final. Their performance was not favored at first, especially considering the tough opponents in the qualifying round. But they got that opportunity and they certainly will not waste it.