No, unless your paid for that week. You'll get it when your manager posted it that it's paid not because the week ended, most managers has lot of errands to do so better keep the avatar and signature hanging until it's fully paid.
Well, technically a user has the right to leave a campaign exactly after the week ends regardless of whether the manager counted the post or not, keeping things aside mentioned by yahoo62278. It just requires a PM from the user to the campaign manager and let the manager know that he has left the campaign after the week ends. But without informing, doing so will result in missing the payment from all the managers. No one has the time travel power to go and check back lol.