It is understood that Lampard will leave the club when his deal expires at the end of the season, though rumours suggest that the 34-year-old could now be offered a new deal.
Benitez praised Lampard's performances this season, but would not discuss whether the club have reversed their decision to let him leave on a free transfer in the summer.
"Frank is doing a great job for us, he's scoring goals, he's playing well, he's a good professional and he's working very hard," said the Spaniard.
"But that's all I can say because I'm the coach. The club doesn't discuss the other issues.
"Hopefully he can break the Chelsea scoring record and I will be pleased."
Lampard has scored 13 goals for Chelsea this season.