Cable delay adds an equal offset to the pseudoranges for all satellites. Since GPS uses the difference in the pseudoranges to each satellite to calculate the position, positioning isn't affected by cable delay.
The position calculated will be at the antenna, not at the receiver, which you can see by realizing that moving the antenna has a different effect on the pseudoranges to different satellites due to geometry, but moving the receiver has no effect at all (the cable length stays the same and so does the cable delay).
The time calculated by the GPS receiver will have an error equal to the cable delay, which is the length of the cable divided by the propagation velocity of the cable. The RG174 commonly used on "puck" antennas has a velocity of 0.66 c, which is about 5 nanoseconds per meter.