I am going to assume you saw the "Grouse Management Area" sign. I can honestly say that I have only seen 1 grouse there in 9 years. But I normally don't go looking for grouse specify. The Ruffed Grouse Society does have many clear cut areas they made in that area though. Between Flatbrook, Walpack, and the Water Gap there are some nice areas to find them. Hard work though.
I used to Pheasant hunt all through that are @ 20 - 25 years ago. Back then you where able to kick up a grouse every now and then. But now, they are very hard to come by. I deer hunt that area and even in the thicker hardwoods area that look like good grouse area, I have not once put up a grouse.