Is it possible to push data in a CSV format from Salesforce to any other external endpoint or FTP server using Data Loader CLI?
Well answer is... no and yes.
So Data Loader CLI doesn't have functionality that would help with that kind of requirement. So it cant maintain Http connection or use FTP protocol other than connection to Salesforce.
But you can place Data Loader on a server that can act as FTP and fetch Salesforce data there. You can use for example Windows Task Scheduler to schedule regular data exports from Salesforce using Data Loader and after that you can connect to that server using another entity and fetch that data. (You can do basically the same with Unix type of OS with Cron Jobs.)