If I restore my Iphone will my photostreams be deleted?
The Photostream itself, populated with photos from the last 30 days(up to 1000 images), will still exist after you restore your phone. However, because of the transitory nature of Photostream, it would be prudent to direct the flow into a more permanent repository such as a computer. 

Shared Photostreams persist beyond the 30 day limit. 

Apple Support articles:

iCloud: My Photo Stream FAQ

iCloud: Using and troubleshooting Shared Photo Streams