No, they don't have all the leverage. You don't have much leverage when you have a player that is signed for only one more season and is vocal that he's likely to walk.
Six teams interested or not, no one is going to give up much to get a guy they might have for only one year.
If Cleveland doesn't budge, they get to keep Wiggins, Waiters, Bennett and draft picks. But if Minnesota is too choosy with these teams, they run the risk of losing Love without getting anything in return. Bottom line is that Minnesota does not have a lot of leverage. They can't demand one player from any given team with running the risk they lose any prospective deals because they made such demands.