The story is here, marred by an unfortunate exaggeration by GLAAD writer Ross Murray:
In 1976 The Bob Newhart Show featured an episode with an openly gay character. It was remarkably groundbreaking for its time.It was not, unless you consider the 12 other shows which aired gay-themed episodes in 1976 also to be "remarkably groundbreaking." (The Newhart character may have been distinguished by being one of the first recurring gay characters on episodic TV, but the GLAAD story did not note this.)
Before the 1976 Newhart episode, (from 1970 through 1975) Wikipedia lists gay-themed episodes of the following television programs:
All in the Family, Sanford and Son, Maude, Mash, Columbo, Marcus Welby, Medical Center, Streets of San Francisco, the Mary Tyler Moore Show, The Bold Ones, Room 222, Dan August (where Martin Sheen again played the gay boyfriend — who got killed), Police Story, Police Woman and Barney Miller.Not listed, (probably because it was a TV movie and not an episode of a TV show) was 1972's That Certain Summer, a Levinson-Link coproduction aired by ABC starring Hope Lange, Martin Sheen, Hal Holbrook and Scott Jacobi, about a father whose son discovers that his dad's male roommate is actually his mother's replacement. Many critics did call that program "groundbreaking."