Are grandchildren of president John Tyler still living in 2013?

Yes, as of 2013, grandchildren of President John Tyler were still living. John Tyler, who served as the 10th President of the United States from 1841 to 1845, had a large family, and some of his descendants were alive during that time. His youngest child, Lyon Gardiner Tyler, had children late in life, contributing to the continuation of Tyler's lineage into the 21st century.