The official occupancy for a 1BR at OKW is 4. You can have a 5th person in the villa if they are able to sleep in a pack & Play, so one would assume under the age of 3.
Anything you hear beyond that is speculation, CMs who aren't following the rules and so forth.
That isn't to say that folks don't put more than 4 people in a 1BR @ OKW. The units are large, and if, for example, you are a family with 4 children, I could easily see Mom and Dad in the bedroom, 2 kids on the pullout couch in the livingroom and 2 kids on the floor on a blow up mattress...there is that much floor space. Make sure you bring your own linens for the blow up, because you shouldn't get any from Mousekeeping.