My question is similar to this how to monitor a text file in realtime
but I want to do it in vim. I know I can read an opened file use tail -f sample.xml file, and when new content is written to the file, it'll also write the new content to my screen. Can I have vim automatically fill the new data when a file is updated?
You can :set autoread so that vim reads the file when it changes. However (depending on your platform), you have to give it focus.
From the help:
When a file has been detected to have been changed outside of Vim and it has not been changed inside of Vim, automatically read it again. When the file has been deleted this is not done.