Wilson Fisk is a normal, baseline human and has had the crap beaten out of him by Spider-Man, Lady Bullseye, and Daredevil recently. He's a tough man, he's survived injuries that would typically kill such as a bullet to the forehead, being impaled, multiple stab wounds but much of that is just owed his training and his physical constitution. He's just a normal man and would be killed almost instantly by the Hulk since he's not as agile as a Daredevil or a Spider-Man and thus able to hold off the Hulk for longer. Plus he's smart enough where he would never attempt something as stupid as getting on the Hulk's bad side in the first place unless he had some kind of high level super-powered operative on his side and he was hiding behind the scenes. Fisk doesn't usually **** with people higher than street level.