I have the VA Regimental History Book on the 51st VA Infantry and looked up Jacob Miller. I found one entry by that name:
Jacob Miller, Pvt., Co. A., enlisted 7/16/61 at Abingdon; detailed wagoner (7/25/61, back in Co,. by 11/1/62) WIA Gardner's Farm (either 5/30/64 or 5/31/64), flesh wound, finger.
I then checked on Fold3 and found his service record confirming the above and there was no entry for his being a POW.
I then did another check for Jacob Miller from TN and found the following:
Jacob Miller, Pvt., Co. K, 53rd TN Infantry. In his service record it stated that he was a POW having been captured at Ft. Donelson on 16 February 1862. He was held at Camp Morton, Indianapolis, IN. Said he took the oath of office on August 21st and was released.