We also booked GTY in hopes of an upgrade. Currently there are 19 different room categories available on this cruise. That tells me there is a lot of empty rooms still
I did a stateroom search of every category (because I am nuts) and found 119 rooms available, as of yesterday.
Disney seems to cap it at 8 rooms per category, in cases where there are more than 8 rooms available. So there could be more than 119.