Hopefully, he will win 6 stages.
There was a remarkable symmetry between the Giro and the Tour. Pogacar won 6 stages in each race. Two sprinters both won 3 stages in either race. And 9 riders won 1 stage in either race.
It's hard to see two sprinters winning three stages in a race with around two sprinting opportunities, though, so this will probably not happen again in the Vuelta.