Well yes, I did read that, and it says nothing whatsoever. Perhaps between zero and 120,000 unnecessary deaths have been caused by austerity then. Would you say it was zero?
It doesn't quite say nothing...it's fairly clear - the authors are claiming causation when they can only prove correlation and other plausible explanations exist.
As for your question, I'd say it's impossible to say without proper evidence, but my hypothesis would be that the figure would be much closer to zero (but not zero) than 120,000.