Yes. Thats 8 drinks per day, binge drinking on a daily basis. More than 14 drinks per week is considered at risk drinking for males. I would suspect alcohol dependence based on this amount. I would suspect he would have difficulty stopping. I suspect you are concerned. I suspect some negative consequences, any consequences have happened as a result. So yes cause for concern. Seek support!
Vodka. Any regular alcohol causes damage to the liver, the stronger the more damage, the longer the use, the more damage, the higher the alcohol level in the blood, the more the damage, to other organs as well. Some individuals are more resistant to damage, others more sensitive. He should be checked for damage, and should stop, with counseling, treatment program, and support.