Assuming you mean Google App Engine with "GAE".
Well the tldr; is: I don't think so.
Maybe you could get it to work, but I don't see a point in even trying it.
An App Engine provides you with a set of services and is best suited for creating small, distributed microservices, leveraging the services provided by the environment.
Liferay portal is kinda an App Engine itself. It is an environment providing a set of services and instead of creating distributed microservices you create osgi services in the Liferay container.
I am not sure what you are trying to accomplish, but if you want to develop stuff using a microservice approach and using GAE, you are probably better off setting up Liferay as an "extra" instance somewhere and use e.g. OAUTH/JWT tokens to combine your microservices with Liferay.
We do something similar at a customer, he has a microservice environment (basically a ton of docker containers) and a Liferay server used mostly as content/document management. An Apache webserver + some single sign on magic glues everything together unter the same domain name.
