The only possible merit to the claim that the Kanye incident helped her, is in the sense that it put her name on the minds of hip-hop fans due to the fact it involved Kanye. That doesn't mean that if not for the incident, "nobody" would care about her. She was an established artist before it occurred, who was already relevant at the time (kind of proven by the fact she was up for, and won the award that led to Kanye's outburst in the first place).
Hell, according to what I'm reading right now, her albums sold in total over four million copies in 2008 alone which made her the artist to move the most units in the year. Not to mention the album she released in that year topped the Billboard 200. That was the year before the Kanye controversy.
Now, if there was clips of it played on an awards show this year, I'm quite sure it was due in large part because of the producers of said awards show and not Taylor personally. I can't really say for certain, as I see about 1 award show every three years (as they're not really my thing), but I would guess that this "re-airing" of it occurred at the VMA's, which it would make sense then for them to play it up on the show since it occurred the year before.
So of course, it was publicity (and even milked which is just good business), but it's not as if that one moment turned her into an overnight success or anything.
PS -- Kanye West's latest album moved 496,000 units first week, Taylor's? 1,047,000. Now, who's relevant? :cheeky:
EDIT: Maybe that's why Kanye was playing it up a few months before his album. With the flood of apologies and such, as well as the claim he wrote her a song. Who knows.