I don't know what this is called. Is it a podium?
I'd say this is a three–tiered rostrum.
A raised platform on which a person stands to make a public speech, receive an award or medal, play music, or conduct an orchestra:
speaker after speaker stepped up to the rostrum
It is a podium.
While technically it may also be called a rostrum, podium is the more common term. This has led to the phrase "podium finish" (usually the achievement of finishing in the top 3), and the awful verb "to podium".