Welcome to the forum.
I just looked up this guy, and all the jerseys he recently sold are definitely fake. The numbers on the Packers jerseys (including the Rodgers) look silver and shiny. They should be white and matt in appearance. Also, Reebok don't make retail authentics with patches any more. The SB patch on this is another dead giveaway.
His other listings are also a giveaway. He sold 2 Giants Cruz jerseys, though I'm willing to bet that Reebok wouldn't have produced any Cruz retail authentics, since he had a breakout year.
The seller does offer a return policy, so worst case scenario, you only have to pay the return shipping. You can also file a dispute in PayPal if you want to get 100% of your money back without incurring shipping, but this will take much longer to resolve.