The question is tricky due the meaning of "survive".
Survival in the sense of "staying alive"? About 300-500 USD per month is enough for me to stay alive. But if we're talking about having a good life, planning a better future for myself and my family, etc, then it's way more, like 2-3k USD per month.
Nonetheless, I'm making around 200 USD per month here on Hive :D So yeah, I'm almost being able to survive just on my crypto earnings :D
Also, !1UP