Type ratings
The long and short of it, not much.
I bought a Citation type because I thought it would give me an edge over my regional airline competition, who were primarily flight instructors. I figured that the type would demonstrate several things, such as (1) that I can be typed; (2) that I had knowledge of turbine equipment; (3) that I could fly turbine equipment to standards, and (4) that I had experienced crew concepts. I also got it because at that time American Eagle was using a Citation sim to evaluate applicants.
Well, I cannot draw a connection to getting the type and getting interviews, which finally happened a couple of months after getting the type. And, having flown the airplane did not help me one iota in the AEX Citation sim. Sims never "fly" like airplanes.
I think the type helped me get the more senior instructing jobs I wanted after I essentially had put my quest for a regional job on the back burner.
While I enjoyed my week getting the type and wrote it off on my taxes, I seriously doubt it helped me get interviews. You need time in type along with the type rating for it to be at all meaningful. I understand that sometimes the FAA will issue a type rating with an SIC restriction. I did not have such a restriction on my Citation type.
Hope that helps.