The Liverpool manager tested Gerrard's mood within an hour or so of the England midfielder's court appearance on an assault charge, and gave him the all-clear to play.
Liverpool's skipper may yet start their sell-out fourth round tie on the bench, but only if Benitez decides he wants to keep him fresh for Wednesday's Premier League date with Wigan.
"Stevie trained really well this morning, and when we finished the session with a five-a-side, he scored two or three goals," said Benitez. "He has not been affected at all."
Gerrard's next appearance at North Sefton Magistrates' Court, on March 20, is less than a fortnight before England's World Cup qualifier against Ukraine.