Is thinning haira sign of cancer or could it be from my fatty liver?

Both unlikely: If the hair is thinning rapidly, the most common reason is telogen effluvium, a poorly-understood response to stress. The most important common entity to rule out is hypothyroidism. If the hair loss is dramatic, a dermatology visit is in order. Good luck.

Probably neither: Thinning hair can be a sign of cancer, but a very late one. Typically before you get to this point you have lots of weight loss, pain, and nausea. Liver disease can contribute to hair loss, but not when you have fatty liver; more when you have the more serious disorder called cirrhosis.