When I block somebody in Viber can he still see my online status? When I block somebody in Viber can he still see my online status? Or will he still receive "delivered" icon?
From VIBER themselves:

What happens when I block a contact?

When you block a contact, you prevent them from contacting you via one-on-one messages or calls to your mobile device on Viber. You also prevent them from adding you to a group conversation.

A few notes about blocking contacts:


You will not be able to send messages or make phone calls to contacts you have blocked.
Your profile information will be visible to the blocked contact if you were saved in their contact list before the block, but they will not see any changes made to that information. If you were not saved in their contact list at the time of the block, no profile information will be visible. 
Your online status will not be visible to a blocked contact
Unblocking a contact will not restore messages or calls they sent while they were blocked.
Calls and push notifications from blocked contacts may still be received on Viber for tablets, Viber for Desktop and Viber for Windows 8.
Blocking a contact will not delete previous message and call history.
Blocking a contact will not prevent you from seeing messages they send in a group you are both participating in.
Blocking a contact will prevent this contact from adding you to a group chat.
Blocked users will see a "Sent" message status for the messages they send you. 
The message status will never say "Delivered" or "Seen"