Does Skywest Airlines have an upgrade or flow to the major Airlines?
First there’s no such thing as an “upgrade” to a Major. In most cases you need to be hired. But to answer your question, no, SkyWest does not have a flow agreement with any Majors. That said SkyWest is a great Regional and many of their employees have no problem getting hired at the Major of their choice, often before pilots with flow agreements.
To my knowledge, they do not.