To sustain and build a community to survive on Mars we will need at least 110 people. Now we have to figure out logistically to get the humans from SpaceX launch sites to Mars and to start terraforming and turning us into multi-planet species and ensuring our survival after an already rough 2020 but this is nothing compared to what real devastation could entail.
Here is the scientific paper breaking down the information on Mars Sustainability: https://www.nature.com/articles/s41598-020-66740-0