Changes in liver function tests are listed as a rare (less than 1 person in 1000) side effect of Zantac.
In general, any drug that's broken down in the liver affects the liver, but usually the liver can handle stuff like that unless you have liver problems already, you're taking an overdose, or you're taking a lot of medicines together. (Tylenol + alcohol can cause liver injury, for example.)
Upshot--it is very unlikely that Zantac will cause a liver problem in someone whose liver is healthy to start with, but if you ARE having problems, there's a chance it could be related.
Definitely, people with impaired liver need a lower dose of Zantac if they use it.