There is ample historical commentary that says it did happen. But because it was written down 42 years later, what we now know as the speech, may not have been the actual speech that he gave.

>Over forty years after Patrick Henry delivered his speech and eighteen years after his death, biographer [William Wirt](https://en.m.wikipedia.org/wiki/William_Wirt_(Attorney_General)) published a posthumous reconstruction of the speech in his 1817 work Sketches of the Life and Character of Patrick Henry.[2] This is the version of the speech as it is widely known today and was reconstructed based on the recollections of elderly witnesses many decades later. A scholarly debate persists among colonial historians as to what extent Wirt or others invented parts of the speech including its famous closing words.

>According to Edmund Randolph, the convention sat in profound silence for several minutes after Henry's speech ended. George Mason, who later drafted the Virginia Declaration of Rights, said that the audience's passions were not their own after Henry had addressed them.[7] [Thomas Marshall](https://en.m.wikipedia.org/wiki/Thomas_Marshall_(U.S._politician)) told his son John Marshall, who later became Chief Justice of the United States, that the speech was "one of the boldest, vehement, and animated pieces of eloquence that had ever been delivered."[7][8] Edward Carrington, listening by a window, was so affected by the speech that he requested to be buried there, and in "1810, he got his wish."

https://en.wikipedia.org/wiki/Give_me_liberty,_or_give_me_death!