Belgium international striker Benteke has been linked with a move away from the Premier League outfit.
Liverpool, Chelsea and Manchester United are all interested in the services of the 24-year-old, according to The Daily Star.
Former Villa manager Lambert believes that Benteke will leave Villa Park in the summer.
"It looks like if he is going to go, it will be this year,” the former Celtic midfielder told BT Sport.
"But I had it every year I was there that he probably wanted to go, because he was playing that well, you can't stop teams coming in with that level of money.
"It depends how Aston Villa want to view it now. If Christian goes maybe they will get money to buy someone. But as a goalscorer and a player, he's top class.”
Benteke struggled to play well in the first half of the recently concluded 2014-15 Premier League campaign, but he came to life when Tim Sherwood replaced Lambert as the Villa manager.
The former Genk star scored 13 goals and created 33 chances in 29 Premier League appearances this season.
The Belgium had a pass accuracy of 67% and a shot accuracy of 45%, and won 187 headers, 17 dribbles and seven tackles.
Villa narrowly avoided relegation from the English top flight, finishing 17th in the league table with 38 points from as many games.