If you decide to stay, I would demand equity, warrants, and/or some kind debt contract. If the company goes under, it would give you more power to be a debtor--not that means anything to help get your funds.
I agree. If management knew they might not be able to make payroll this month they should have laid people off last month & paid up any/all outstanding wages. The fact that they didn't means they are making decisions that do not respect their employees interests or existing employment contracts.
I'd stop work immediately, quickly make copies of any documents (timesheets, email trails etc) capturing some evidence of days of work you have done that have not yet been paid for, and switch to full time job searching for an actual job.
Send brief written communication that you regard any previous employment agreement as broken since company is unable to fulfill its side of agreement by paying wages, state how many days unpaid wages you are owed and request payment.
When applying for new jobs, if asked why you are looking, frankly state that you are looking for work as your previous employer was a startup that ran out of money to cover payroll. Anyone who is vaguely professional will immediately understand.
For another point of view, see: https://www.askamanager.org/2012/09/my-company-isnt-paying-u...