Hi Sarath, do you have a Chat server setup on your CS application ? That's the first step to escalate a Facebook interaction to an Agent. You need to create a queue on the chat server called "Facebook". Then, when you are talking to the Facebook bot, you can ask to "speak to an agent", "human", "chat" or a few other keywords and the conversation would be escalated to the agent.
Only caveats here are that you need to make sure the correct applications are being used. There's a Facebook channel that's shipped OOTB with all the functionality built right in. There's also an application that the agent should be using, so the infrastructure for talking to the Facebook messenger is built in. All of these features work OOTB, the only thing you need to do is to provide the Chat server, create the queue and make sure your Facebook channel user and Agent are using the correct application layer.
Trying to boost the visibility of this question as I have a similar request - how do we escalate from the pega chat bot (not Facebook, but the web chat channel) to an agent/CSR? It seems like such a common request that this should be an easy to enable feature.