Yes it's open. Just got back from a trip on Friday and we used it several times during our trip. There is a dedicated security checkpoint there for folks arriving via the walkway, and it was never busy.
Resorts monorail is running mostly normally as well, with the exception that it's not currently stopping at the Poly while they finish the new Poly Lobby and monorail station. It does appear that they are looking to have the Poly back to normal sometime in July. But things can always be delayed. As previously mentioned, when we wanted to go to Poly, we got off at TTC and used the walkway from TTC to Poly.