Is the government intervention to alleviate poverty sustainable over a long period of time

I don't believe so.
Government intervention (such as welfares) is actually a good policy to help poor people sustain themselves for a short period of time .
But, in order to fully eliminate their poverty, Government should focus itself to help poor people get a good job to sustain their own living, otherwise, the Government just hemorrhaging expenditures and increases national debt overtime

What document are you referring to