Pull content from production to staging server
Content is particularly difficult to Migrate. It's not as clean as Configuration. Generally, what you are talking about is not done - as Kevin points out, content is created on prod, and databases are pulled from prod to any other environment that needs that content. That said you could set up a Migration strategy with the Migrate API that could be used to migrate content around between environments. You're mostly on your own with this though - I haven't seen any tutorials for your specific issue.