yes, and they still do.
They could, in theory, if the Greek gods actually existed, which of course they don't.
The gods in Greek Mythology were just legends. Such as Atlas the god that held the earth and sky, and Zeus the god of all gods.
There is not really an answer to that but the twelve gods were born to be gods
The Greek gods are part of Greek mythology meaning they never existed. And if they did then they would still be around. The answer is either "never" or "forever". Since it was a religion and, thus, had answers for every possible proof against it it is not able to be proven wrong or correct.
Before the gods were the titans who were rules by Cronus
The Titans existed before the gods and were more powerful.
The first gods that existed were Uranus and Gaia. Hestia, Posideon, Hades, Demeter, Hera, and Zeus were their grandchildren.
No, not really. The only 'religion' they have is greek!
Nobody knows if the Greek gods really lived but most Greeks would say they would because of their religion.
The gods did not really have birthdays.
There are 100 Greek Gods, but there are only 13 essential Olympians that are really recognized and mostly taught about and studied.
Only for the ones who believe in them.