Estimated account value is based on the actual STEEM, SP, and SBD held in the account.

Steem Power says (+8,760.505 STEEM)

This actually indicates delegated account power. That means the SP is held in somebody else's account, but they have assigned (delegated) their voting power to @kittybot.

So @kittybot is able to vote somebody else's SP (because it was delegated to them) and have more valuable upvotes.
In the case of bidding bots, the delegation usually comes from investors, who then receive a share of the SBD that is sent to @kittybot for bids.