Interesting, does everybody speak it in Ireland as a first language?
Maybe 50,000 people. Most people have some Irish from school.
It would have died out if it wasn't for its association with Irish nationalism - there was a big cultural revival from about the 1870s - during the few decades before we rebelled from the UK, with Irish-speaking social clubs (and Irish dancing), the setting up of the Gaelic Athletics Association (who run hurling among other sports) and an effort to promote the literature of Irish writers, particularly in theatre. All that mirrored a peaceful independence movement, but when that failed to achieve independence, the IRA took the lead. All this is a bit of a simplistic picture, but it'll give you an idea.
Is it somewhat releated to english language, some different dialect maybe?
No, it's quite independant. There's a celtic branch of languages it's part of - Irish, Scottish, Welsh, Cornish, Manx, Breton. There were mainland European celtic languages in Spain, France, the Benelux region and some of Germany, but they gave way to Latin (French and Spanish are essentially dialects of low Latin which have drifted apart a bit over a few centuries) and Germanic languages. English was originally Germanic (the Saxon bit in Anglo-Saxon), but has a strong Latin influence, mainly from the Norman invasion of England - French was the language of the upper class in England for a number of centuries.
Here's a map of the regions where Celtic languages were spoken:
and here, in a nod to the purpose of the thread, is a picture of a bunny with a pancake on its head: