Are White Cats Always Deaf?

No, not all white cats are deaf.  Usually, if a cat has blue eyes and is white, then it will be deaf, but this is not always the case.  Some cats for example, the Turkish Vankedisi is a purely white cat, with blue eyes, but usually has normal hearing.  

However, within the standard 'cat population' cats who are purely white and have blue eyes will be deaf.  It is suggested that this is because the white gene which causes the fur to be white, actually affects the development of the cochlea in the inner ear and this is why the cat is deaf.  It is usually an inherited and genetic disorder and may cause some very slight facial differences from other cats.
  
Deaf cats may be more at risk than their hearing counterparts, for example, they will be less aware of oncoming danger, but usually they manage to lead quite contented lives.  They can feel vibrations both in the ground and in the floor and so compensate for their lack of hearing by developing other senses.

No not all white cats are deaf.
chances are if it had blue eyes then it could be deaf.