How do i know once all my pictures are safe in iCloud?

If you use iCloud Photo library, you can always see them. See this article:

Set up and use iCloud Photos - Apple Support

BTW, you don't add the storage to your iPhone. iPhone physical storage and iCloud virtual storage are two completely different things and one cannot substitute for the other. iPhone physical storage cannot be upgraded. If you are running out of storage on your iPhone, see the "Save space on your device" section in the above article.

ema245 wrote:

I would like to purchase the 50GB of storage for my iphone to be able to keep my photos safe, but how will i know that all 1,000+ of my pictures are safe in iCloud?

Define safe.