Wii U will likely end this year around 5.5m units sold lifetime which is about 1.5m behind Gamecube in the same time frame.

http://www.vgchartz.com/yearly.php/?date=2011&reg=World&date=2003&console=&maker=

According to this Gamecube sold about 6.3m in its second full year. Can Wii U beat that in 2014?

Possible, it's a Mario Kart plus Smash Bros year versus a Zelda plus Mario Kart year (although i still contend Zelda U is possible for 2014).

I don't think the WII U will be able to beat it unless it drops the price to $200 when MK8 releases.

Wii U's 2014 lineup looks quite a bit better than Gamecube's 2003 lineup (sorry Double Dash), so I'd say yeah. Wii U might even pass the GC in total aligned sales by the end of next year.

close. still wiiU only can go up. while GC sold well at the beggining but rapidly faded away

i think it will about the same as gamecube

Yes.