Gonzales made the claim in a YouTube video, saying Take Me to Church was "almost the exact same" as the song released in 2011 - two years earlier - by Feist.
Hozier's manager Caroline Downey has described the allegations as "groundless" and confirmed to the The Sunday Times Ireland that she and her client will seek legal action.
Hozier, born Andrew Hozier Byrne, recorded the soulful, bluesy hit Take Me to Church in the attic of his parent's home in Bray, Co Wicklow. The lyrics take issue with the Catholic Church and its stance on homosexuality.
"I was just fumbling around and I came upon the idea for a chorus," he told Rolling Stone in January, "then I went up into the attic and made a little demo."
The song quickly became an unexpected global sensation, reaching the number-one spot in 12 countries.