a 64GB iPad has 58Gb of useable space.There is no way you could have 59Gb free. more like 59MB which would then account for the lack fo space if your iPad is a 16GB version you've pretty muched filled it up. As a 16GB iPad will likely top off at 14Gb or so.
Thanks! I just did a hard reboot (suggested from reading other posts about other issues). And the status amounts changed! Now it makes more sense, I have 73.4MB available and 13.8 GB used. It's just a 16GB iPad, so I've used it up.