On the one hand it seems a bit of stretch from a liability standpoint. On the other hand there are theories floating around that Holmes choose that particular venue - as opposed to theatres closer to where he lived - because of its lack of security and layout. The theatre routinely had police on duty for the weekends but because it was a Thursday night there was no police presence - despite advance sales of sold out midnight shows in multiple auditoriums and an anticipated large crowd. [Heck in NYC they had police at various multiple Apple stores yesterday due to the anticipated crowds for the IPhoney 5 going on sale.]
I doubt Cinemark has enough insurance to cover all of the victims. In fact I have to wonder if they might not be self insured. Therefore I would expect them to fight the lawsuits - particularly the first ones - pretty hard.
Kind of surprised that Warner Brothers was not also named as a defendant - considering that the frist trailer for Gangster Squad (containing the theatre shooting scene)had been playing since early May. But maybe that will be a separate lawsuit.