The former AS Roma midfielder came on in the 76th minute of the contest after missing the beginning of the season with an ankle injury and Benitez was pleased with his efforts.
"There were a lot of players showing passion, character and quality on the pitch, and Aquilani was one of these player," said Benitez.
"He has the quality, but he needs to improve his match-fitness.
"You can see he can pass the ball in the final third, he can make a big difference.
"He gets closer every day, but still has to improve his match-fitness. It's a question of time."
Benitez added that he expects 25-year old Aquilani to become a key player for Liverpool.
"I think that he will be an important player for us," he added.
"We want to push him, but we cannot push too hard as we know that will be a risk.
"So we will keep going, keep working and add more minutes every game."