Qintriples
They would be decuplets.
Quadruplets.
Brothers
If you mean "What are eight babies born on the same day called?": Octuplets (if born by the same mother)
Eventsakes
I don't think there is an answer.
Unrealated twin
They are two in a set of triplets.
OverCast Kids
People born on the same day are commonly referred to as "birthday twins" or simply as "born on the same day."
about 490,000
Your birthday!