Currently, just me and the wife. However, we have 3 unused bedrooms too (one is a craft room/home office, another will be a game room/home office, and the other is a guest bedroom). But, we also have a den that could easily accommodate a king bed, and the shop space, which could easily have a few beds.
It also would not be difficult to just pasture the horses, and convert 10 stalls into individual rooms (just add a wood floor, and a wood wall over the stall bars, and furniture).
We've got 4 bathrooms, so that helps. If converting the stalls though, I'd have to put in an outhouse out there (it's a long trip from there to the house)....
So, us (2) plus 2 in each bedroom (6), plus (2) in the den, and likely (4) in the shop....add that to (10) in the stables, and we're at a max of 24 we could house, and still have private space for. I think that's a pretty decent, solid number.
Of course, that assumes we don't get with the neighbor, and house some with her too. Her home is nearly as big, and just her...so she'd likely welcome some defenders/providers too.
In any case, pretty sure the ranch could easily support a couple dozen people, as long as well all worked at it (and dedicated a pasture to gardening, in addition to the garden).
There are at least 5 close friends and relatives who may come to us, if things went south...so we have room to grow as time goes on. Evaluating potential newcomers is really one of the scariest problems of a post SHTF world.