Lille is second in the table, two points behind PSG - which drew 2-2 with Bordeaux - and above Lyon, Monaco and Montpellier on goal difference.
Lyon continued its fine form with a 3-0 win over Reims, as Monaco beat Nimes by the same scoreline to also move within two points of PSG. Montpellier edged out Lorient.
Lille would have hoped to take all three points from a Saint-Etienne side on a seven-match losing streak in the league before kick-off.
Christophe Galtier's team fell behind to a controversial first-half penalty from Tunisian Wahbi Khazri and needed a second-half strike from Jonathan Ikone to rescue a draw.
Galtier was left frustrated by the decision to award Khazri the spot-kick, after the former Sunderland winger appeared to fall over Domagoj Bradaric in a vain attempt to reach the ball before Lille goalkeeper Mike Maignan.
"The penalty was a clear refereeing error," he said. "Wahbi Khazri comes with a lot of experience onto my player Domagoj Bradaric.
"With video and professional referees this shouldn't happen. It doesn't take away from our bad first half, but it was an important moment of the game."
Lyon looking 'upwards'
Karl Toko Ekambi, Bruno Guimaraes and Moussa Dembele scored for Lyon as they made it 16 points from their last six matches.
"We must continue in this vein and look upwards. We must put a run of victories together," said Lyon coach Rudi Garcia.
"This is the first time that we have won three times in a row. As in Angers (last week), we had an opportunity to (move up the) table. We seized it."
PSG gave the chasing pack a chance to cut the gap with a 2-2 home draw against Bordeaux on Saturday, having blown a two-goal lead to lose to Monaco last week.
Reims, who had Moreto Cassama sent off on 33 minutes, remain fourth from bottom and look destined for a relegation dog-fight.
Monaco march on
Monaco eased to victory over Nimes to notch their fourth straight league win.
Young midfielder Sofiane Diop gave the hosts an early lead at the Stade Louis II, before Gelson Martins and Kevin Volland struck in the second half to see off Nimes, who had Lucas Deaux dismissed in the 69th minute.
Germany striker Volland has scored five Ligue 1 goals for Monaco since his close-season move from Bayer Leverkusen.
The principality outfit have finished ninth and 17th in the last two seasons and coach Niko Kovac was eager to play down any thoughts of a repeat of their shock 2017 title triumph.
"The title? Not after 12 games, we're not there, no," said the Croatian.
"It's a good period for us, we have to keep working, we are a young team. We will also lose matches."
Fifth-placed Montpellier also extended their winning streak to four matches as Petar Skuletic scored late on to grab a 1-0 win at Lorient, despite midfielder Teji Savanier's missed penalty in the first half.
Marseille, which has also won four league matches on the spin, is only four points behind PSG in sixth, with two games in hand.