Out of all the people who played the Bloodborne demo at TGS, only 40 of them managed to beat it.
The statistics are courtesy of producer Masaaki Yamagiwa and marketing manager Yasuhiro Kitao, who held an event and had a chat during it about the number of people who tried the demo at both PAX Prime and TGS versus the number of those who finished it.
Attendees who tried the demo at PAX Prime amounted to 3,500 and only 20 of them killed the Cleric Beast, the demo's end boss. At the Tokyo Game Show, 1,250 attempted it and only 40 of them managed to kill the beast.
So you can believe Brenna when she says the game is more aggressive than any other Souls game.