Rangers need seven more points from their last eight games to confirm winning a league that they have dominated from start to finish.
Gerrard has earned plaudits for gradually building the Rangers squad since 2018 and finally jumping at the opportunity to win the league once Celtic faltered badly this season.
The former midfielder has a contract until 2024 and there is little indication that he could consider leaving Rangers in the summer.
Foster believes the challenge for Gerrard is to inspire his players to go and win the league again next season in order to turn his Rangers side from a good to a great team.
The former Rangers star said on PLZ Soccer: “I have heard Roy Keane say in England that the true test of champions is can you win the league and can you go and win that again.
“It looks like Rangers are going to win the league this year but if he stays, can they repeat it and do it again.
“That’s when you start to get a team into the record books as one of the great teams who can go do it over the course of a number of seasons.”
With Rangers expected to win the league, they will directly enter the Champions League group stage next season and are likely to have more money to spend in the summer as a result.
