Not much!
If you pass the ATP written, CAAC medical and can provide all the notarized documents (police check, no accident/incident record, certification of flight time, etc) that they want, you will be offered a job.
No technical questions at all. "Why do you want to work for us?" "Have you been to Shanghai before?"
"How much time in airplane, etc" and "what was your last employer", but that is right on your CV.