While this is a tangent, it's an interesting one! I don't think anyone has done great empirical testing on the income demographics of Wikipedia administrators. It looks like income was not included in the 2011 survey; it does say that 42% of all respondents were unemployed, but this is likely driven by the number of students and minors.
In any case, "poverty line" is a subjective definition that varies dramatically by jurisdiction. In the U.S., approximately 15% of the population lives below the U.S. definition of the poverty line. Given that, it seems extremely unlikely that 18% (or even 15% or 10%) of American Wikipedians live below that line; for other jurisdictions or definitions of the line, it seems hard to speculate.
On the larger question, I'm with Jamesofur that I don't think supporting Wikipedians financially (other than via fellowships as part of the program budget) was ever on the table. Or at least if it was, I certainly didn't hear about it.
~Nathan