The Dark Knight appears to be the most pirated film in 2008 according to io9.
However, The Dark Knight is also the 2008 highest grossing film in the US and it is the second highest grossing film ever in the US after Titanic (unadjusted for inflation).
How did piracy adversely affect The Dark Knight?
It appears not to have been affected by piracy.
How will DRM prevent piracy?
It does not prevent piracy.
How will DRM prevent consumers from consuming media?
It does so by accusing consumers of being pathological pirates.