Hey guys I have a quick question, how many years do an era equate to? 1000?

It looks like a new era starts when some big event ends/takes place. I don't think it's a fixed amount of time.

It lasts however long it needs to.
The First ended when the Reman dynasty fell.
The Second ended at the start of the Septim Empire.
The Third ended when the Septims fell and the Oblivion Crisis ended.
The Fourth could end at the end of Alduin's 'World Eating phase', we don't know.

Alright thanks. That's actually pretty cool.