Firmino netted the second for Tite's side when goalkeeper Pedro Gallese's clearance ricocheted off the 27-year-old and struck the post before he finished into an empty net with 19 minutes on the clock.
The Liverpool No.9 then delivered an assist for Dani Alves' second-half strike that made it 4-0.
Brazil are now through to the quarter-finals of the competition after topping Group A.