If you closed the contract, then the client may never provide feedback. And there is no way you can force the client to provide feedback.
If you closed the contract, I believe there is a 14-day window during which the client can provide feedback.
But also: Keep in mind that your client MAY ALREADY HAVE given you feedback, but you may not have seen the feedback yet.
Feedback can take a few days - even a week - to show up on your profile page.
So after a job is closed, I always look for feedback in a place it appears immediately: I click on the listing for the contract in the section in "My Jobs" tab that lists all contracts, including closed ones.