Forward Yilmaz scored the opener in the 11th minute as Lille led the first half 1-0.
Lille doubled the gap in the 47th minute as Jonathan Bamba put the ball into Lens net.
Jonathan Ikone made it 3-0 for Lille in the 69th minute.
Turkish midfielder Yazici clinched the large win, scoring the fourth goal of the match in the 79th minute. Lille boosted their points to 17 to lead the league. They have won five matches and had two draws in the 2020-21 season.
Sunday's losing team Lens had 13 points to come fifth in the league table. This season the French league saw an exciting struggle for the leadership.
Second-place Paris Saint-Germain, and Rennes, who currently sit in the third spot, had 15 points each to chase Lille.
Nice, the club from France's south, bagged 13 points to be in fourth place.
