Okay. So. I've actually been looking into this today, and I'm not sure ive figured out exactly what brand it is, but I think ive at least got a few pretty good options.
Sweater: https://www.amazon.com/dp/B01M3VK210/ref=cm_sw_r_cp_apa_LhlgybE564JQG http://m.jcpenney.com/st-johns-bay-long-sleeve-solid-crewneck-sweater/prod.jump?ppId=pp5007980046&Ntt=&Ns=featured&N=&page=1
I think that the jc penny one might actually be the sweater he wears. But who knows.
As far as the jeans, I have no idea how you'd figure out exactly what brand they are. They're so generic and he's been wearing them for the past 8 years, honestly.
And bonus, Amazon recommended me the dinosaur shirt he's wearing in his two most recent Instagram posts, so enjoy: Ragstock Men's Casual Button-Up Icon-Printed Woven Shirts https://www.amazon.com/dp/B01KP2MOZQ/ref=cm_sw_r_cp_apa_yllgybHZD2AX8
Hope you still care about finding it out, lol.
EDIT: fixed the jc penny link