Finding a job in Rio de Janeiro will largely depend on your command of Portuguese and special skills that you have to offer.. It's a moneyed city with plenty of cheap labour so the usual jobs of waitressing, labouring or working in shops are unlikely to be open to you.
It's also very hard to get a work visa in any case unless you can prove that you're offering a skill that Brazil lacks. A Brazilian company can apply for a work visa for you and if you end up teaching English it's just possible that your school will do it for you. They may not expect you to stick around that long though and so will probably be reluctant to go through the whole bureaucratic process.
The pay for teaching English in school is distinctly unimpressive but good money can be made giving private classes or teaching at corporate level. If you give private lessons make sure you get your Brazilian students to pay in advance as if not they may decide to go the cinema rather than come to class.
If you're good on the phone and your Portuguese is good you might be able to sell yourself as an expert English teacher to a large company. You'll need to look the part and be prepared but teaching to businessmen is a lucrative way to make a living. We imagine female teachers might have the edge here.
Another option if your Portuguese is good and you're able to cut deals and sell a bit, is to make money from the other dumb gringos who need someone to find them an apartment, take them on tours around the city, translate and generally trouble-shoot. Don;t try to sort them out any drugs though unless you want to have a Brazilian adventure in jail. If you ever got out alive you'd never be the same again.
Whilst Brazil is a cheap country overall, Rio de Janeiro can be an expensive place to live. As a traveler here staying in a budget hotel, eating street food and taking your chances on the buses, you could exist on $25 a day. If you like your fine tastes and have a lot of fun when you travel then it would be easy to part with $40-100 a day.
Rio de Janeiro is one of the pricier parts of Brazil and how much you spend really depends on where and how you choose to live. You can get by on about $750 a month by taking buses, cooking for yourself and heading out to the street parties.
If you take taxis everywhere, eat out and hit the most chic of nightclubs then it can work out as a costly place to live - let's say around $1400 a month,