Polls don't really mean a thing, and popularity in the ballot doesn't matter either. I hate using overly used terms but, a lot of people would call it a big suggestion box, rather than an actual ballot.
On the ballot itself, it said that they would "consider" the characters voted in, and from sakurai's history, he's gonna pick the most out of whack, never before seen character, and better yet, put his own spin on him/her.
This ain't the first smash ballot either, there has been plenty of other ballots in the past, where more obscure characters made it in over the top 5 characters.
Rayman's got too much going for him right now, from the originality, right down to the trophy of himself in the game, I wouldn't be cocky about his chances, but I wouldn't worry about it either, honestly. If he doesn't choose rayman, then oh well, he probably just couldn't come up with anything for him.