Here is the best gate breakdown for Delta in ATL that I can come up with...I hope it's right but things do change often at ATL:
T-Concourse: 8 gates
A-Concourse: 34 gates
B-Concourse: 36 gates
D-Concourse: 10 gates
E-Concourse: 22 gates
Total 110 gates
ASA (DL Connection Carrier) has 16 gates in the C-Concourse. Combine the two and you get a grand total of 126 gates for DL.
Note that no airline officially owns the gates in International Concourse E.....however because of DL being the home airline and having the most int'l flights, DL has preferential use of 22 gates.
Currently, there are a total of 167 gates at ATL....although four more are currently being added onto Concourse E.
American uses gates T9, T10 and T11.
United uses gates T12, T13 and T14.
Airtran uses gates C1-C20.
The remaining gates in Concourse D are used by CO, NW, US, TW, Vanguard, Frontier, Midwest Express, Midway and a few others. I can't remember the exact gate numbers for all of these.
The remaining gates in Concourse E are used by Air France, British Airways, KLM, Swissair, Lufthansa, Air Jamaica, Aeromexico, LAPA, Korean, South African Airways and some charters as well.