Humans will have no reason to believe it, and the machine will have no way to prove it. Humans have no other reason to think other humans are conscious except by analogy to themselves.
edit: mainstream science at times has denied that babies, black people, and animals feel pain. Instead, it has suggested that when injured, they behave in a way that causes (white) people to project their own pain onto them; i.e. they anthropomorphize. I mention this to point out that even the analogy to other humans fails when they look a little bit different.
Yeah, so the discussion is useless. It’s not very interesting; our ‘consciousness’ might be a million year old system prompt or it might be something divine. There is no proof either way. For me it’s just a second brain thread that keeps pouring in prompts from the main thread brain and your input hardware.
Also; ‘it’ will know it has consciousness when it has it, arrogant humans will still deny it.