Piracy has nothing to do with this movie's sales (well, maybe it does, a link to a torrent of the movie was on the front page of Reddit within a few hours of it being available to stream online). What this case study shows is that your movie can do well online if you have a few weeks of non-stop press coverage about a controversy surrounding it, your company gets hacked into and terrorist threaten to blow up movie theaters if you show it.
The Washington Post is reporting that it only made about $2 million at the box office. it also says on Dec 25th alone it was illegally downloaded 750,000 times. I would imagine at least a few of those people might have bought a ticket.