For sterilization, you need to boil something for a minute or more.

Generally, the boiled water is poured into a room temperature container over top of room temperature tea leaves. The tea itself is never supposed to boil.

So, since it hasn’t been boiled to sterilization, no, it’s not sterile.

But if the container is sterile and the tea/teabag has come pre-sterilized, you’ll be pretty close.