Posts (articles and also comments) are always evaluated 7 days after they were published. And then upvoting or downvoting has no impact.
You publish, then people vote and then (after exactly 7 days) it is evaluated and you get the author reward.
Here is an example. https://steemd.com/b/37225196
You can see down there the "Virtual ops" part. There are those transactions that are not signed, but are computed by the witness who produced the block (and checked by other witnesses). You can see at that page that there is one post evaluated - author and curators get their rewards.
After this evaluation, no subsequent voting, or downvoting, will impact the rewards, no other evaluation will happen for the article (at least with the current settings). (But the mana of the voters is deduced).
I hope that this answers your question. Have a nice day.
EDIT: Downvoting after the 7 day period will not even hide the post (from what I have tried).
Thank you for the info. :-)