The reigning champion goes 11 points clear of Monaco as it edges past Les Merlus in the Stade du Moustoir.
The PSG head coach had come under criticism from Gourcuff recently for his "hands-off" approach, but was able to celebrate after Thiago Motta's first-half goal sealed a sixth consecutive win in Ligue 1.
After neat work from Zlatan Ibrahimovic, it was Motta who slid in from close-range to find the net for the third time this season.
Lorient thought they had grabbed an equaliser in the closing minutes when susbtitute Bryan Pele fired beyond Salvatore Sirigu, but the 21-year-old was flagged offside, much to the relief of the PSG defence.
Les Parisiens move 11 points clear of second-placed Monaco, which hosts Lille on Sunday, while Lorient remains eight clear of the relegation zone and will still be looking nervously over its shoulder having played a game more than the teams below them.
The visitors initially struggled to get into the game, with their time on the ball in the attacking third restricted by Lorient's effective pressing.
PSG was still dominant in regards to possession but the hosts offered a real threat on the counterattack, and had an excellent chance to move ahead in the 15th minute.
Vincent Aboubakar was released down the right and muscled past Maxwell before touching the ball to Yann Jouffre, but the midfielder's shot was pushed away by Sirigu.
Midway through the half there were concerns for Blanc as his captain Thiago Silva was forced off with a head injury, and PSG's frustrations grew when Edinson Cavani wasted a free header on 38 minutes.
Despite being far from its best, the reigning champion was able to take the lead four minutes before the break as Motta scrambled the ball home following excellent work from Ibrahimovic.
The Sweden international was a key figure in a move that led to Cavani having a shot saved and Ibrahimovic then showed quick feet to force the ball towards goal again, with Motta beating Bruno Ecuele Manga to poke over the line.
The capital club began the second half with more attacking intent and Ibrahimovic had claims for a penalty turned away before seeing a dipping volley well-saved by Fabien Audard.
Lorient felt it should have had a penalty of their own prior to the hour mark, but replays showed Alex had clipped Alain Traore outside the area and the referee did not even award a free kick.
Blanc's side should have doubled its lead on 75 minutes when Cavani broke clear of the Lorient defense on the left. His low cross found Christophe Jallet at the back post, but the fullback's low shot was somehow kept out by Audard with his left leg.
Aboubakar wasted a fine chance to level with five minutes to play as he headed wide from an unmarked position at the back post, and Pele thought he had snatched a point only for the assistant referee's flag to rule out his 87th-minute strike.