The name of the beer is sometimes spelled in France "Gueuse", obviously under the influence of the feminine form of the original word. Gueux and gueuse are no longer in use in modern French except as a conscious and usually facetious archaism.
I love the story of "We are all Gueux". (It's a similar reaction to injustice that the French students showed in 1968 when Danny Cohn-Bendit was expelled from France: "Nous sommes tous des Juifs Allemands!" (We are all German Jews!")) And what the word means still today in Flemish and Dutch. Great story.
Hats off to Helen's encyclopedic knowledge of beer, too!
So it's one of those "ping-pong" words that are borrowed by one language and sent back again, sometimes twice over.
The first recorded use in the French language of Gueuze or Gueuse for the beer is 1900. There's a cross-reference to a similar beer, Faro (a Walloon word).
