AE might have some 80% of the home enthusiast and motion graphics markets maybe.
In mid and small sized boutiques doing film or high end commercials work it's usually a satellite app for some stuff at best, when present at all.
In larger (usually nix based) studios it's not even an option at all, except maybe a couple macs or win boxes kept around for other things might have it on board to use some particular feature or plugin for it, but it's relatively rare. That figure would be kind ridiculous to begin with, but without a context it's downright absurd.
Who told you that anyway?
As for what you should learn, it depends from what you want to do.
AE will do such a good job of messing up your work and hiding the internals that it's a terrible platform, particularly for colour, but if you plan on working at a TV station or doing motion graphics somewhere, it makes you extremely marketable.
For film work Shake is still widely used, but it's dead and being replaced quickly.
Nuke and Fusion are taking its place.
