Sure - upvotes and 'downvotes' (reporting a post) affect the post reward payout at the end of the first 7 days following the post being published. The more 'Steem Power' you hold in your wallet, the more of an effect your up or downvote will have. Someone who holds a million Steem in their Steem Power 'box' will be able to upvote posts/comments by a significant amount - probably valued at hundreds of US dollars per vote, whereas a million votes from users who have virtually no Steem Power will result in very little effect in terms of increasing or decreasing the payout.

Upvotes increase the payout and downvotes decrease the payout.