The whole quote shows what a dummy he is. First he says he’s been to 57 states, then says he has one more to go to. Then says that his security detail hasn’t let him go to HI or AK, which is two states not one. What a maroon.
He starts to say 50 states. Then realizes he hasn't actually been to all 50. So let's see, how many has he been to. Well, taking the 48 continental states minus one left to go, that's 47. So he says the "seven", having forgotten that his previous word wasn't "forty". So the correct tally would be 47 of the lower 48 states, which is to say all but one of the states other than Alaska and Hawaii.