If it's 5 Jem'Hadar vs. Data in an empty room in a random encounter, the Jem'Hadar are probably all armed and Data probably isn't. It sounds like you're working on a role playing game.
There are no weapons involved. I'm just curious if 5 Jem'Hadar could take Data, but the concept now seems laughable, if Timo (Star Trek genius) is correct about their strength level.
Perhaps a better battle would be 5 Hirogen vs. Data or 5 Gorn vs. Data, though I'm sure if Data really went all out he could one-shot either of them.