Cnut was the grandson of Harald Bluetooth, and Harold Godwinson was the great great grandson of Harald Bluetooth. What would that make them to each other? Did they ever know one another? If so, what was their relationship like? Thank you!
Harold's descent from Bluetooth is debated and uncertain, but if he was a blood relation, he and Cnut were first cousins twice removed. Forkbeard and Thyra were siblings, Cnut and Thyra's son Thorkil would have been first cousins. Thorkil's daughter Gytha was Harold's mother. But there is no solid historical evidence that Thyra married Styrbjorn the Strong and gave birth to Thorkil.
However, Gytha's brother Ulf wed Cnut's sister Estrith; it's not a blood tie and Harold couldn't have called Cnut "uncle," but there were some links.
I do not know if they met. I'm shaky on pre-Conquest monarchs and don't know how much time Cnut spent in England as opposed to his other lands. But given the connections above and the fact that Cnut died when Harold was about 13, I'll say it's possible and leave it at that.