Substitute Benzema scored with almost his first touch on 65 minutes to put Real 1-0 up in the Champions League last 16 first leg but Gomis netted seven minutes from time to stretch Lyon's unbeaten run against the Spaniards to seven games.
Real are confident they can complete the job at the Bernabeu on March 16 and make the quarter-finals for the first time in seven seasons, having at least broken part of their Lyon jinx by leaving the Stade Gerland with a first ever draw.
But Lyon have managed a draw on their three previous visits to the Spanish capital and matched the nine-times winners for most of Tuesday's match.
"Having conceded the goal, we showed character and had the chance to come back, which gives us an opportunity for the return leg," Gomis told reporters.
The tall, dreadlocked striker blew a first-half effort with the goal gaping in front of Lyon's noisy Virage Nord, who never stopped singing all match and even cheered former hero Benzema.
"I knew I would get another chance and I just had to keep my cool," Gomis added.
"It's good for Karim but of course I'd rather he hadn't scored."
Brazil winger Michel Bastos was one of Lyon's top performers in the cold and rain but misses the second leg after picking up a booking.
"It will be hard for Lyon," Real coach Jose Mourinho said after prowling his technical area nervously for most of the game. "But in my opinion it's 50-50."
