I can only speak for SWA, but you will not get a job at SWA if your 1000 TPIC is dependent on Caravan PIC. Single pilot PIC on a multi engine A/C will be a little better, but you'll always get passed up for somebody who has multi-crew turbine time. SWA hires Captains. If they can, they want people with a track record of dealing in a crew situation. Nobody denies that a King Air is a complex aircraft, but what if you came in with 1000 hours of single pilot EclipseJet time? You might make it, but it will be much much more difficult that if you had time that actually means something.

Bottom line; any experience is good experience, but if you're trying to get to a major, I would look for things with multi-crew environments, and would certainly not rely on Caravan or VLJ time. Again, only SWA, I can't speak for the other majors.