I have bruxism and some hearing loss, could it be my eustachian tube blocked fully?

Unrelated. Bruxism and hearing loss are unrelated. You may have hearing loss because of eustachian tube dysfunction. However get checked with your doctor.
Not likely. Bruxism (habitual grinding of the teeth) and other disorders of the temporomandibular joint (the jaw socket) can cause pain that is described as an earache. Eustachian tube blockage can cause a painful middle ear infection or blockage of hearing. These diseases are commonly confused, because both cause pain, but they are not related.
Eustacian tube. The nerve that controls our jaw muscles also controls one of the muscles associated with the eustacian tube. In some people with tmd, they will experience a fullness in their ear and the feeling of having hearing loss.