You can definitely live in Brazil with 1K USD/month.
And nowadays it's even better because the USD-BRL rate is about 5-something. For a comparison, 1K USD is about what I spend every month to live - and I definitely don't cook beyond just breakfasts and some snacks/sandwiches. So I lunch in restaurants every single day, I live in a quite comfortable apartment, etc. - I mean, I'm not "stretching myself to spend as minimum as possible". In fact, 1K USD is about 4x the BR minimum wage, and about 2-3x the "common" income of people.
I live in Fortaleza, a very sunny city which is close to some incredibly beautiful beaches. Search for "jericoacoara" on Google and you'll know what I'm talking about (Jeri tends to be a bit expensive tho, due to heavy presence of tourists - but not much).
Fun fact: it's quite common to hear about gringos coming around and deciding to stay. You'll find some French and Italian restaurants in Jeri and/or Jijoca - and lots of gringos, of course.