Another fun fact, the current population in Ireland is about 5.3 millions. That means there're more Irish in U.S. than in Ireland.
But it also says that the year before the shit completely hit the fan, the Ireland population topped out at 8.18m. 10 years later it was down 1.6m, and another .6m after another 10. And it just kept trending downwards until the 1930's, (4.21m) and bottomed out again in ~1960 before it started growing again.
Hyperbole is a common facet of humour (to make a point) in the British Isles.
Btw "Gaelic" alone typically refers to either the language family - Scottish, Irish, and Manx - or specifically to Scottish Gaelic. Irish Gaelic, in English, is simply referred to as "Irish" or "the Irish language". And it's largely the source of the way the Irish use English.