Well....

Some lived, many died but according to my list: 10,076 were victims to Wo Fat including the arch-nemesis himself (beaten and punched in the final episode during his fight with McGarrett). This is counting about 1000 people (figured about 900 attendees and 100 cops) who tried to stampede out of the circus when Wo Fat yelled, "He's got a gun!" in S07E12 "Presenting...In The Center Ring...Murder". This is without counting the hypothetical victims: victims of episodes where Wo Fat wasn't there but could have been working behind the scenes (i.e. Chinese spy rings, Chinese bidders for people or equipment).

With the hypothetical victims counted: 10,114.

No one has to say it, I know I'm insane. If you're interested, I have Tony Alika's numbers too. Although I think I only counted those he killed.