That article is incorrect...and it was also written before The Avengers was even done at the box office.
Also, from the same article:
KnossisTicket sales aren't the gage of success, money is. TDK took awhile to hit its total and it had to be rereleased to do it. Not to mention, plenty of folks probably waited and caught it at the dollar theaters on the cheap. So your numbers are off to begin with. Avengers doesn't have to make 18 mil to surpass TDK in ticket sales. When it hits the dollar theaters, as all films do. It could sell 5 million more tickets and only make 5 million. You need to factor in everything. And if TDK gets a rerelease to prop up its numbers, so does the avengers.
Again, the bottom line is this; Dark Knight did it's thing. It made a lot of money. Adjusted for inflation it lost to Avengers. PERIOD. WB didn't want to spend the money to make it in 3-d? Boo Hoo. That's on them. It cost them and it cost TDK it's bottom line.