$109 rebuy, been betting alot, 40 bb's, Raised 2x button+2 with J8s , called by the big with 50+ bb's, avg player and kinda tight.

Flop 4d 8h 8d, Pot 4000

Villian checks, bet 2500, called

Turn 9s, Board 4 8 8, 9 Pot 9000

Villian checks, bet 4000, raised to 9000,

20k left in my stack, what would u do?

And would greatly appreciate any help on the chances of being outkicked for the different 8x combos here.

Really pretty impossible to answer in a meaningful way. If he plays ever *8 hand then there are 45 of them if I counted right. (We have seen 6 cards, assume he has an 8, that leaves 45 unseen). There are 3 J8s you tie with, 4 Q8s 4 K8s and 4 A8s for a total of 12. So 15/45 times you're splitting or losing, usually losing.

But is it really as likely for him to have 82 as it is A8? I doubt it. When he has an 8 it's probably heavily weighted towards A8, 78, 89, 8T. Further, when he really likes his hand, possibly you discount the lower *8 hands in favor of the bigger ones.

Also you lose to 44 and 99, there are 3 combos each of those.