There are 10 different versions of the AC-130, so they can be placed in BR 8.0 to 10.3/10.7
The “lowest”, the AC-130A “Project Gunship II” has only 4 M61 Vulcan and 4 “minigun” MXU-470 MG - so it is not usable against tanks.
In the middle we have the AC-130H “Spectre” with a better engine, 2* M61A1 “Vulcan”, 1* Bofors 40mm L/60 and 1* M102 howitzer.
The latest version will be the AC-130J “Ghostrider” with 1* ATK Mk.44 “Bushmaster II”, the M102 howitzer and 10* AGM-176 Griffin, 8* AGM-114 Hellfire, 10* GBU-44/B “Viper Strike” and 4* GBU-39 or GBU-53.
An AC-130 would be useless against aircraft, so I think it would be a combination of the gameplay of drones and WW2 bombers.
The AC-130 could use the reconnaissance drone function and automatically make wide circles over the battlefield while the player uses the on-board weapons.
The first Version(s) absolutly - but the later versions with guns like the 40mm or the 102mm could be nice.
For example, the Spectre should have a relatively high effective range with its 40mm and especially its 102mm.
It would be reasonably protected from regular AAM and, thanks to its own range, reasonably protected from AA guns.
Really dangerous for the AC-130 series would be probably every airplane and also some helicopters.