I actually only know one goddess of poetry of the Celts...Brigid (also know as Brie, Bride, Brigit, Brigante) She is considered the Irish goddess of Inspired Poetry, Healing and the patroness of Goldsmiths. Taliesin is considered a major bard, but not a true god, the same is true of Amergin the Druid. "Celts" is an umbrella term, are you speaking of the Irish Celts only? Or all the peoples that can trace ancestry to the Celts? If you are doing that, then, of course there are many gods as these are all separate tribes and nations.
The Irish are a nation of poets, it's true. It is part of the Celtic nature and make up. I know, I have Celt blood within me myself.