I have employed foreign high tech workers. I am very leery to do that anymore. Typically, they work well until near their visa is set to expire, then they ask for financial aid to help pay the humongous cost of special immigration attorneys who help them with their paper work. The last time I went through this game the attorney showed my worker that he really needed a 50% raise in pay. I showed my employee a survey done within this state by a trade association that listed salary ranges for most of the engineering fields of people employed. I also showed my employee a different government produced survey that said his current salary range was appropriate.
His attorney said that he absolutely needed to have a significant raise to show the critical need for his skills or he wouldn't have a strong case to make to immigration.
At that point he started immediately looking for other employers. He really didn't perform after that.
This high tech worker thing is a scam all the way around from the attorneys that benefit to the foreign workers looking for a way to get into and stay within the US.