investment property finance question

I have heard on the radio that most banks are only willing to allow a person to borrow up to x7 their annual income.
Is this true?

So say john makes $50,000/yr, he in theory should be able to borrow $350,000 to buy an investment unit right?

Now, does the amount of deposit you have affect this number?

Say john wants to borrow $350,000 for an investment unit, he would need say $35,000 cash deposit right?

Lets say john has $100,000 cash, would he still only be allowed to borrow $350,000? or would he be allowed
to borrow more?

thanks a lot.