What is the longest running cable tv show?

The first premium/pay cable network was HBO. It launched in 1972 for New York City & then expanded its service to other providers, by 1975 HBO was starting to be seen countrywide.

The first basic cable network was launched by Ted Turner in 1976. It was WTCG which stood for Turner Communications Group. He soon after changed its name to TBS which stands for Turner Broadcasting System.