If you're asking if Splunk can index the log files and hold the data for you, acting as an 'archive', yes it can do that. Instructions on how to do this can be found here
If you're asking if Splunk can take the files and move them to an archive location for you, not it can't. Splunk will only read your files in their current location, it won't edit the contents or move them for you. It can be configured to delete the files once it has indexed them, but that's a specific configuration setting you have to add yourself.