Unfortunately, you can't see who blocked you on Viber. There is no app, feature, service or menu to access or use to see that. Viber pretty much keeps this information private due to privacy reasons. You won't see it appear anytime soon for any of the platform supported by them.
However, if you know someone that uses Viber day by day and didn't reach back after you contacted them or don't appear on your friend's list, then you know for sure they blocked you.