Yup, the W gene which causes the white fur is pleiotropic, which means it influences several traits at the same time (in this case eye pigmentation and the internal ear). However there are several other genes involved which allows for some variation. Most white cats with eyes other than blue are not deaf, but they can also be. If a cat has one blue and one yellow eye, he's probably deaf on the blue side.
Also a fun fact, white cats have an underlying fur pattern but it is hidden by the dominant W allele. A white cat with blue eyes might be a Siamese with a masked pattern.