According to Business First, it won't be started until it's 40% leased. It's an awfully big building, so I have to question whether it gets built. The rendering on BuffaloRising shows it behind the proposed new federal courthouse, I think, which also seems to be in limbo at present.
More info here:
http://forums.speakupwny.com/showthread.php?t=9685 (see message #10)