@GurpreetKaur You can also try to use the Google Pub/Sub Push Subscriptions as TomF mentioned.
You can setup a subscription to a Solace REST service URL (Web hook) like this https://:/TOPIC/ in order to publish the messages to a Solace topic.
If authentication is enabled, Solace would require a REST called to authenticate against the broker before it is able to send a message.
The GCP Push Subscriptions use OAuth tokens for authentication, which can be validated on the Solace broker by setting up an OAuth Profile with the GCP client token details and an OAuth group to provide specific access to the GCP service client.
Let us know if this solution is of interest to you and/or you need some more help.