After contacting a maintainer of the bundle he provided this solution which answered my question:
Have a look at this https://github.com/dustin10/VichUploaderBundle/pull/200/files
Keep in mind that the bundle is triggered by entity lifecycle events (onPersist onLoad etc), but it will only manage the copy if an instance of UploadedFile is injected in the entity.
if you want to manually create the file but still manage it with the bundle you'll have to inject and UploadedFile in the entity.