Not sure. When I arrived at GRU in Terminal 3 earlier in April on an international flight, the corridor to connect to another international flight was open at the time. This would allow one to stay airside and not need to go down the escalators to Passport control. I would suggest talking to the airline you will use as if a Brazilian visa is required, they should know and would not let you board the flight to Brazil without one. Of course, obtaining a Brazilian visa eliminates any concerns.