Did you watch the whole interview or read it? There is no mistake. He thinks that on his knuckles was “M S 1 3” in Arial font in real life. The interviewer tried to give him the out, said that the tattoo could be interpreted that way, and then tried to move on. But Trump doubled down multiple times and said that there is no interpretation. That the literal letters and numbers were tattooed on him. So, there is no ambiguity to what Trump is insisting is true. You can question whether he is actually stupid enough to believe that (he is), or just thinks that his followers and the media are stupid enough to believe it (he does), but there is no longer any question as to whether Trump is claiming that the literal letters are tattooed on him. He said so unequivocally.