Currently, if you plug two controllers into the Xbox One, then attempt to browse the console's bootflow from controller two while FIFA 14 is loading, the game will often crash. Until you've patched your game, EA's support site suggests plugging a single controller into your machine until after you've cleared the game's initial loading screen.
Likewise, if you're browsing the bootflow while at the FIFA 14 title screen and allow the console to lay idle long enough to activate its low-power suspend mode your game may crash. EA's solution to this issue is simple: don't do that. If you can't help yourself though, and find your game has crashed, reboot the Xbox One.
While today's patch should fix the above problems, EA notes that there are still numerous issues it is looking into. For instance, players are currently unable to join a "Friends Only" match from another player's Xbox One profile, and crashes are common when playing in co-op Season mode if a team's captain is using custom formations while his or her partner is not. There's currently no word on when these problems and the others listed on EA's support site will be fixed.