If you go to Youtube and search for Halo 4 trailer. the highest viewed video has 6,464,444 views since the video was released 6 months ago..
Now go and search for GTA 5 trailer it was released a few weeks ago and it already has 10,290,539 views.
I think this just shows how popular GTA 5 will be..
GTA 5 trailer
http://www.youtube.com/watch?v=QkkoHAzjnUs
Halo 4 trailer
http://www.youtube.com/watch?v=TC2yMKMENdg