Gerrard damaged his hamstring in Saturday's 1-1 draw with Blackburn Rovers.
"Steven will not travel. He has a problem with his hamstring," Benitez told reporters on Tuesday.
"If it was the last game of the season he would play, but with Sunday's game (against Manchester United)
"It is a big loss for us though because Stevie can change games."
Midfielder Momo Sissoko is likely to play despite a calf problem, but Dutch striker Dirk Kuyt is a major doubt with an ankle injury. Striker Robbie Fowler has not travelled to France because of a back injury.
Liverpool top Group C with four points along with PSV Eindhoven.