I would say about 1 1/2 quarts or a bit more.
BUT the beauty of the traditional recipe is that more or less broth works as well!
TASTE as you drain the solids and if too flavorful add some water or if you think it is not as tasty as you like it, boil it down to reduce a bit and intensify its taste. NOTE that the egg and lemon you will add will also impart LOTS more FLAVOR too.