Brad Pitt. Gangsters. The two seemingly were destined to spell box office success for the Weinstein Co.’s “Killing Them Softly.” Guess again.The stylish dark crime thriller from director Andrew Dominik, opened wide to a meager $6.8 million over the Nov. 30-Dec. 2 Stateside frame, one that’s traditionally sluggish — though unusually robust turnout for holdovers meant execs weren’t willing to blame the weekend. On the contrary: Weinstein chief operating officer David Glasser and prexy of distribution Erik Lomis say the post-Thanksgiving slot was a solid launchpad for the pic. “It definitely wasn’t an arthouse film,” Glasser says, adding that a summer release date would have been far too competitive. “It was always about scheduling the film on the right date.” Weinstein originally slated “Killing” to bow Sept. 21, but then moved the pic to Oct. 19. The eventual date positioned “Killing” as a more visible awards contender. Still, Weinstein has been preoccupied lately with “Silver Linings Playbook,” which has cumed more than $11 million domestically to date in platform release. As for “Killing,” Stateside prospects look grim: The film received an F CinemaScore, though that’s likely because most auds weren’t expecting Dominik’s highly stylized take. The pic has fared better with critics. Playability through the holiday season will provide some extra oomph, more so than during any non-holiday play period, at least. But “Killing” is likely to exit theaters as it entered them — softly.