The word guzzle first occurs in English in the late 16th century. There is no certainty about where it comes from, though it is probably imitative, based on the sound that people make when they swallow food or drink quickly.
The charlatan Daniel Cassidy, in his ridiculous book How The Irish Invented Slang, disagreed. He claimed that it comes from gus óil, which he claims is an Irish phrase meaning ‘a vigorous drink; high-spirited vigorous drinking , (act of) gulping down a drink, to drink with great vigour, to drink greedily.’ It doesn’t, of course. The word gus means ‘force, vigour, resource, enterprise, spirit, gumption, self-importance’. Óil is the genitive of ól, meaning drink or drinking. If gus óil existed, it would probably mean the tendency to be arrogant or fired up because of taking too much drink. It wouldn’t mean guzzling.
I suggest you copy the phrase “gus óil” and put it in a searchbox in Google. See if you get any hits unrelated to Cassidy! In fact, do it with all of Cassidy’s made-up rubbish and you’ll get the same results.