Do you have any data to be released on steam or just staying in gog ?
Historically, there have been Star Wars games released on GOG that later ended up on Steam, with some of GOG's fixes. Pretty sure this was the case with the X-Wing and TIE Fighter games, the Rebel Assault games and Rogue Squadron, so I'd expect Episode 1 Racer to end up there eventually.
That said, it's not really so cool to be asking on GOG for when a game that they've only just released here will end up on one of their competitor's sites. GOG would likely have negotiated some deal with Disney/LucasArts for some limited exclusivity before other sites get to sell it, so they won't be giving that information away as it would undermine their potential profits from selling the game.