There was a book written about the John Clough family of the same area in Essex Massachusetts and neighbors of the Gills.
http://johncloughgenealogicalsociety.org/john-clough-immigrant-ance...
I found the book online and copied a few pages as I recall starting on pg 40 to pg 43 (you should be able to find it easily enough too) - which describes the kidnapping of young Samuel while he was "out berrying" with an older young man that day. I even looked up the time of year for berrying then because I am related to the Gill family via the Indians who took him and raised him.
The book as I recall now was something like the John Clough Family and the Indian Wars ....
From a quick search online just now, I found this too: (background)
https://ancestors.familysearch.org/en/KLZK-VNL/john-clough-1678-178....
So there is a lot on John Clough and his family, but the book mentioned above is the one in which he talks about his friends the Gills (some spell it Gille or Guille) and how the father went at least 3 times to try and talk his son to come back home. The son was adament he wanted to stay and was happier.
Strange but true story, and this eyewitness tells the tale (John Clough) as he tells his family's life story in Massachusetts.