Hey Brodie - welcome to the Forum, great tune! Yes, a G harmonica was a great inclination, however he’s actually playing a Natural Minor tuned harmonica in the key of Am. That’s why you can’t get that one note! If this song really inspires you, I recommend purchasing a Lee Oskar Natural Minor harmonica in the key of Am. I think Hohner also has some line that they do the Natural Minor tuning.
Which notes you play on the Natural Minor harmonica will be different, but you will adjust quickly, and then find it’s much easier to play, and you can get your missing note!
Aloha,
Luke