He's not an official saint, which I think is a really rotten deal. I mean, just because you're fictional doesn't mean you can't be revered.
Not that he's totally fictional. Probably. Saints.SQPN.com ("notes about your extended family in heaven") writes of St. George, "Soldier. Martyr. That’s all we know for sure."
Maybe that's a healthy way to approach all of the saints--and each other, actually. How little we know for sure. Who knows what kind of dragons people are facing every day?