When I was there 2nd week of December, the ban was posted at the comfort station on the bulletin board. However, I think that stays up 365 days a year. Supposedly, they are allowed if not dry season (whenever that is in Florida) as long as the pit has a fully screened cover. That being said, I saw sites using them while I was there, covered and uncovered. I suppose you would have to call and ask.
I have a 'Little Red Campfire' which is a LP powered 'campfire in a can' style fire pit. From what I understand those are not allowed as it is 1. LP powered and 2. has no screen cover. I would think these would be safer as it it not that big a fire, no sparks and can be instantly shut off.
But, Disney rules is rules! Enforced or not, they get to make them, it's their property.