Honestly, I think it comes down to mentality. As morbid as it sounds, men are used to toughing it out because that's what's expected of them, so are more likely to survive short term homelessness. And if you survive it in the short term, you have a good chance of surviving it in the long term.

Not to mention that men are probably more likely to already be abusing such substances before becoming homeless as an established coping mechanism, whereas more women probably start abusing those substances after, leaving them less experienced to avoid overdosing, or otherwise more prone using drugs in ways that threaten their health.

Either way, this isn't an issue of the difficulty surviving on the streets, it's an issue that people are forced to survive on the streets in the first place. Shelters are nothing more than a stopgap, and the city and province should be focusing their efforts on both preventing people from becoming homeless, as well as habituating those that have fallen that far.

Especially as once you become homeless, you lose the ability to get a new job since nobody will hire someone who arrives at an interview with bundled cloths and smelling of piss because they have no ability to get a shower.