The length does to an extent. Depends on his setup and what he's using. 100BaseT is what he's probably using, meaning that he has 100 yards (about 300 feet) to work with before he'd run into losing data signal.
The length shouldn't matter in this example, and i don't think the cable is the issue since he can see the network (or is connected w/o internet). Have you manually entered the default gateway? Have you rechecked to make sure your default gateway is correct on your router? Do you have your router giving out IP's? Have you tried an ipconfig/renew in the command line?