There is no such thing as sponsorship for a tourist visa. He must apply on his own and qualify on his own.
I would definitely not marry on the first visit - not only is that a red flag for immigration, but you do not know the person at all.
My advice is to meet in a country that doesn’t require a visa (or offers something like visa on arrival or eVisa) for either of you. Take it slow, there is no need to rush into a marriage with a stranger.