The idea of resistance is an interesting one... examine the idea of Guerrilla Warfare, operating in scattered, informal, and often illegal ways. Check these names out: 

Adbusters (Kalle Lasn), Architecture for Humanity (Cameron Sinclair), Pierre Bourdieu, Design Corp, Che Guevara, Michel Foucault, Heavy Trash, Jersey Devils, Kick Start International, Light (Jae Cha), Mad Housers, Carlos Marighella, and Rural Studios (Samuel Mockbee).

Maybe this will help you somehow... 

Above suggestions are great. Check out JR's work (graffiti artist).

Banksy

Some (more) names worth checking: 

Marc Angelil and Rainer Hehl ETH: http://www.angelil.arch.ethz.ch , recently did a book called Building Brazil, have written on Favelas, political economies of urban space. http://vimeo.com/34796368

Actually, you should check out the entire symposium that the last video is from. http://vimeo.com/album/1793079/page:1/sort:preset/format:thumbnail , Lectures from Francis Kere and Fernando Garcia Huidobro for instance could be helpful although they're not directly talking about Favelas.

Estudio Teddy Cruz 

Leo Lambert ( http://thefunambulist.net ), a French blogger who writes extensively on militarized architecture, and resistance.

Nice links above, but I think that the focus of the project may be sidetracked by the literal interpretation of resistance... 

Correct me if I'm wrong, but I understood your take on resistance as the creation of art... how the act of self expression in the form of an investment in cultural capital is a form of resistance. Your thesis is actually quite complex and requires a lot of research... one of my professors from college has an entire foundation dedicated to this research. He also teaches a class called Guerilla Altruism. Google It. 

When you say favelas and art, I really hope you don't mean this. 

Yes, I agree with you Bulgar...I don't intend to lead anyone off-track of what sounds to be a potentially very interesting thesis. Rather, I simply posted some architectural thinkers who have been influencing me a bit lately and who (at least tangentially) have a connection to the topic at hand.

Assuming this is an architecture thesis (and not cultural anthropology, sociology, etc), I think a key challenge will be to bring this discussion of artistic resistance and creative production into the realm of architecture.

This all depends on how you define architecture... if you consider architecture as a social practice, then your research can involve an analysis of human behavior and how that takes place or has the potential to take place in a built environment. Perhaps your project can be a critique of the existing or a proposal for a new infrastructure that may alter the way that behavior takes place. 

i am more focused on how their art is a way of resistance 

I think it is a mistake to compare the resistance of Bansky to the type of resistance seen in the favelas.

one is individual, intentional, and direct resistance through the use of image and placement, and the latter is more of a collective, indirect resistance stemming from a need to beautify and give value to a seemingly undesirable place.  By giving beauty to the blight, the place gains a cultural value and indirectly resists the states ability to eliminate it....It gains relevance through its "vibrance" The "art" hides and eases the undesirable poverty and crime making it culturally acceptable in the eyes of the public.  It would be much easier to crack down on favelas if no one noticed them and if they did not contribute to the identity of the city. 

Lebbeus Woods discusses favelas in Anarchitecture:  Architecture is a Political Act and generally deals with the idea of resistance.  Given the nature of his output, his work might be worth a look.

resisting what exactly? the gangs and drug lords? the police? a subversion to a gentrifyng capitalism?

careful. its pretty easy to overlook basics and fetishize the trivial. have you read any good books on the favelas, their history and the daily routines of their inhabibtants' lives?

my problem with many of the above suggestions is the incination to turn such places into a fashionable dystopia more as as a fuel for a blasé and ill disciplined imagination where there is a dearth of convicing associations.

good luck

Spot on, tammuz, spot on.

To OP, I would suggest you do a careful reading on favelas and have some understanding of their intricacies and subtleties. Unless you live in one, your view point will be one of an observer and what I often witness is the caricaturing of favelas that doesn't add to the discussion.

Also you should be able to substantiate that "art is a way of resistance" within this context.

Good luck.