I'm not sure if that's accurate. I know that there are 1.5 million seniors receiving the guaranteed income supplement, both married and single, and of course those who are married receive it at the married rate, which is lower than the rate for seniors. What we do know, though, is that single seniors are more likely to be in low income on GIS, whereas for couples—you're right, there are still some who are in low income—the two sources of income for couples are more likely to raise them above the poverty line, the low-income line.
On October 18th, 2016. See this statement in context.