Can you receive a VAT refund at the airport if you are on a DTV tourist visa?

I think so. I've had no issues getting a tax refund with a non-O marriage visa. I think they only look at your passport, in practice anyway. They don't allow Thais to get tax refunds and in theory, permanent resident aliens (who are foreign nationals) and some other categories aren't eligible either, but in practice, it seems that any foreigner gets a tax refund.