Who has the winning hand in this Texas-holdem scenario?
Yes, it is a split pot. Both players have AAKK8. You always make your best 5 card hand from the cards available. From Wikipedia:


  A hand always consists of five cards. In games where more than five cards are available to each player, the best five-card combination of those cards must be played. Any cards not included in the hand do not affect its ranking. For example, if player A holds 3♠ Q♦ and player B holds 3♣ A♣, and five cards 4♣ 5♦ 6♦ 7♠ 10♥ are available to both players, the players hold equally ranking 3-4-5-6-7 straights despite the fact that the player B's ace ranks higher than the player A's queen.