The date of death of 1869 only eliminates the Thomas L. Smith in the GA 55th. He died in Cedar Hill, TN in 1890. The other three I listed are the ones you should research first.

I didn't list other possibilities, but there are many. I use www.civilwardata.com as my primary research tool, and have made many connections using it. However, the records of the Confederacy are scant, and most records did not give date of birth, age, or home town; no data base has a complete listing of all who participated. Also, I supplied you only the listings for a Thomas L. Smith in TN and GA. Also, many records from the WBTS did not even give the given name of the soldier; ie, there are records of 23 Thomas Smith in TN (no middle initial) as well as 23 Thomas Smith in GA. There are also two T.Smith in TN records and 2 T.L.Smith in TN, 8 T.Smith and 1 T.L.Smith in GA records. All could be the man you seek.

Good hunting!