How do you say Noah in Gaelic?

There isn't a direct translation of "Noah" in Gaelic (either Scottish Gaelic or Irish Gaelic) because it's a Hebrew name. Gaelic names would typically be chosen based on meaning, not direct transliteration. If you wanted a Gaelic name with a similar meaning (related to comfort or rest, depending on the interpretation of Noah's name), you'd need to choose one from existing Gaelic names. There's no single "Gaelic equivalent."