The wildlings and the men of the Night's Watch and even some northmen are all pulling for the Giants, of course. But in the Vale of Arryn and the Mountains of the Moon, they're Falcons fans.
The Lannisters are cheering on Detroit, even if the lion is the wrong color, but some of the smallfolk of Lannisport on its western bay are fond of those 49ers. The High Septon and all the septa and septons and devout of the realm are for the Saints.
The butchers and tanners of King's Landing and Oldtown are behind the Packers, the smiths and armorers are with the Steelers. At the Citadel of Oldtown, the archmaesters and the Conclave are all about the Ravens, but across the narrow sea the khals and Dothraki horselords are screaming and whistling for the Broncos. In Volantis, the tigers are Bengals backers; the elephants are rooting for whoever plays the Bengals.
Nobody anywhere knows what a 'Texan' is, but a few Dornishmen might support them anyway, just to be perverse.
One commonality unites all the Seven Kingdoms, and the lands beyond. Everyone everywhere hates the Patriots, and Evil Little Bill.