The Blues will need to turn over a 2-0 semi-final first-leg deficit at the Liberty Stadium if they are to reach the Capital One Cup final at Wembley.
Terry had been out of action since November before coming off the bench against Stoke City earlier this month but did not appear in the two games that followed, and Benitez refused to reveal if the skipper would play a part in the cup tie.
"He was training, he was doing well," said Benitez.
"As I said before, he lacks match fitness, but he's training well. Yesterday we had a hard training session and he was doing well. Today he was training again.
"He's in the squad and he is an option."
Chelsea face Swansea at the Liberty Stadium in their Capital One Cup semi-final second leg on Wednesday.