I would think Gaia would have released a Castlevania knock-off item by now, after Lords of Shadow....
If you notice, gaia tends to do that. When Assassin's Creed was released we got assassin gear, when the Robin Hood film was released we got a Robin Hood item, when Bioshock 2 was released we got a big daddy item. And there are even more releases that coincided with items than just that! My bet is that the next rig will have a Castlevania themed item, or an artist will sneak some themed poses in somewhere. Hey, maybe that's coming up in Antique Shop! Mark my words. It may just take some time.
Heck, do you know how many years it took for them to make some Gungrave themed items? They were only released just last year. One came with the halloween event, so that wasn't too far back.