Ah, sorry, I didn't think you are using the frame sequence export. In that case, the answer is: no, the atlas data doesn't store any pivot information. But you can setup a fixed pivot as follows:
- Add a transparent background image that will bound the skeleton, so no part of the skeleton ever goes out of that background images bounds.
- Record the position of the origin relative to the background image
- Export to sequence including the background image
This way, all exported frames have the same size, and the pivot is a fixed point in each frame.