Companies who donate money to candidates love H1B visas.
End of the day, H1B visas don’t affect that many American workers, and they people they do affect can still find jobs. It’s not the same as a factory being shut down and workers in a city not being able to find anything close to as good.
If Trump does go after H1B visas it will be more theater than policy based. The people who elected him care a lot more about factory work and Mexican laborers than they do visiting Engineers and Computer Programmers.