I am working on a PC AI that is based off of a Drone Autopilot program

He would have a piloting skill but what would his dice pool be ? as per a drone or something more ?

is the Pilot skill for the AI be used for the "Pilot" of a Drone ?

PC AIs are for the most part like any other hacker. So his dice pool would be Pilot <Vehicle Type> + Command.

Don't confuse the Pilot skill for the Pilot program, they are very different things - he would use the skill when remotely controlling a drone, whereas the drone would use its Pilot attribute + Maneuver autosoft (if it has one) to control itself.

Page 204, Unwired, or page 247, SR4A. You'll be looking at the "Jumped-In Rigger Dice Pool," not "Autonomous Drone Dice Pool." I believe Aerospider directed you towards the "Remote-Controlled Dice Pool."

Don't forget you'll need to buy the Pilot Origin quality to be able to jump in.

With the Pilot Origin you can use Autosofts, which includes the Maneuver autosoft.
So if you don't buy Pilot Ground Craft you can use Maneuver (Groundcraft).
The Maneuver autosoft is equivalent to the vehicle skills

Vehicles, Drones, and Agents. A little shameless plug.

EDIT: There's nothing really there for AI players except the program options and efficiency of drones that I have worked on. So while I don't call out AIPCs specifically, the thread benefits them by association.