Gateway Aggregation pattern is similar with Gateway Routing but extra it is offering aggregation of services. Basically Gateway Aggregation pattern offers to use a gateway service that provide to aggregate multiple internal requests to internal microservices with exposing a single request to the client.

This pattern is should be used if client application have to invoke several different backend microservices to perform its logic.

https://medium.com/design-microservices-architecture-with-patterns/gateway-aggregation-pattern-9ff92e1771d0