Agreed, I don’t understand why this isn’t obvious. What he said was this:
“Let’s say I’m debating Pocahontas,” Trump explained, “I promise you I’ll do this: I will take, you know, those little [ancestry] kits they sell on television for $2…[standard bloviation, yadda yadda] …And we will say, ‘I will give you $1 million to your favorite charity, paid for by Trump, if you take the test and it shows you’re an Indian.’
So he HAS promised to make that offer if and when he debates her, but clearly did not make the offer then and there. It’s disheartening to see people (and “news” websites) intentionally leaving off the “And we will say”.