It's the clash of the titans, and there are many important factors to consider.
Firstly, let's not forget that during the last generation of consoles (PS2, Xbox, GameCube), Grand Theft Auto vs. Call of Duty was laughable. I mean, it wasn't even close.
CoD didn't really start its dominating run until Modern Warfare in 2007; prior to that, GTA had torn up the sales charts since GTAIII hit in 2001. Also, it's important to remember that GTAIV did sell upwards of 20 million copies in its lifetime, which is at least in the vicinity of the biggest CoD titles. No other franchise even comes close.
So, could GTAV outsell Ghosts this year? I'm not sure it can outsell CoD long-term; in looking at the sales charts for each month, the latest Call of Duty always seems to make it into the top 10. It really is a year-long sales phenomenon. Does GTAV have that kind of staying power? I'm not so sure. But maybe it has a chance to outstrip Ghosts in 2013. I mean, it'll have a two-month head-start and let's face it, many industry experts and analysts have predicted a backslide from CoD this year. Even Activision admitted that Ghosts probably won't be shattering sales records the way previous iterations did. Pre-order numbers are lagging, it seems.
Besides, gamers have been waiting on the new GTA for a long time. GTAIV released in April of 2008, which means it has been nearly five and a half years since we last saw a new entry. CoD comes around every year. Sure, you can keep selling it to the mainstream masses but the core gamers are very likely more tuned into GTAV right now. Therefore, given all determining factors, maybe it isn't crazy to think that GTAV might knock CoD from its lofty holiday perch…
Related Game(s): Grand Theft Auto V