Informal and mildly derogatory. For neutral or clinical contexts use 酗酒者 (heavy drinker) or 酒精成瘾 (alcohol addiction).
usage
鬼 is commonly added after nouns to create informal/pejorative terms for people obsessed with something: 烟鬼 (yānguǐ, chain smoker), 懒鬼 (lǎnguǐ, lazybones), 小气鬼 (xiǎoqìguǐ, cheapskate).
culture
酒鬼 is also the name of a famous Chinese liquor brand (酒鬼酒) from Hunan province.
