Lets look at the evidence my fellow SU and IZ fans 8Dlets start with aesthetic
Both are small Green aliens around the size of a 11 year old child
Both use Robotic limbs to seem more intimidating Ok now similar IZ moments in SU
Peridot thinks the toilet is a portal?
and Zim made his lab entrance a tollet.Fear of RainPraise me! Similar Evil laugh
Both create their own technology, both hate earth and cursed that they are stuck on it.
Both confuse madame earth Objects for powerful tools
Both hardly have a inside voice and yell ridiculous
both are very short tempered and break things when angry.
and if that ins't enough for you!
the final concrete evidence to this theory
Rebecca Sugar creator of Steven Universe use to have a Invader Zim fan fic blog when she was younger.
I believe Peridot is Rebecca Sugar's homage to Invader Zim, what about you?