https://www.pcgamer.com/nathan-fillion-says-he-doesnt-believe-cayde-6-is-really-dead/

Destiny 2 took a hard turn into unexpected territory last month at E3, when fan favorite Guardian Cayde-6 was killed dead by Uldren Sov during a big breakout from the Prison of Elders. Since then, Bungie has adamantly and unequivocally insisted that the killing is real, and Cayde-6 is dead. But Nathan Fillion, the voice actor behind the character, told Kotaku that he doesn't buy it. 

Fillion began (at around 6:00, after talking about a short Uncharted fan film he starred in that was released today) by saying that he's not actually involved in the Destiny 2: Forsaken expansion at all, which would be why he's speculating on, rather than simply spoiling, the ultimate fate of Cayde-6. "I wasn't available for this last installment. It's not me doing the voice for Cayde-6," he said.