Club captain Terry, 32, missed last season's Champions League final victory over Bayern Munich through suspension and has not started any of the Blues' last three games.
Midfielder Lampard, 34, who is one goal shy of equalling Bobby Tambling's record of 202 goals for the club, is in the final weeks of his contract, with uncertainty over whether he will still be at Stamford Bridge next season.
However, Benitez said there was no room for sentiment in his team selection, with the starting XI for next Wednesday's final against Benfica still to be determined.
"What I can say is that Lampard will play against Aston Villa (in the Premier League on Saturday) and I cannot say anything about the final," Benitez said.
"The only player that I can guarantee today who will play against Aston Villa is Lampard. The final, I don't know. I haven't decided [the team] yet."
And Benitez declined to reveal who would be starting in the centre of defence in Amsterdam.
"The competition in this position is really hard here," he said. "[Gary] Cahill, [Branislav] Ivanovic, David Luiz, they are doing well, too.
"Now we have four centre-backs, they have to compete and they are doing well."
Benitez again backed Lampard to break the record and hopes it can be accomplished against Villa - to make his final team selection more straightforward.
"I have confidence that he will do it," Benitez said. "He can play one more game and after see what will happen in the other two [games].
"If he can score against Aston Villa it will be easier for me in the last two games.
"If he scores two goals against Aston Villa, we'll begin to talk about what we will do.
"I will do what I have to do to win games and if at the same time I can help Frank, I will do it."
Chelsea may be without Eden Hazard (calf) and Victor Moses (leg) for the trip
to Birmingham, while Ryan Bertrand (knee) remains out.
The Blues hope victory at Villa Park will confirm their Champions League return, after a draw with Spurs on Wednesday delayed their bid to seal a top-four place.