Cinéad IV is right. It's terribly difficult to compete against the USA's plurality, unless you are lucky enough to get an ahistorical USA in the game.
I have two basic strategies that seem to work as Brazil. The first is to concentrate on cultural techs while keeping an eye on the SE Asian countries waiting for one to get really bad prestige (-100) so I can start conquering some colonies. Some days I'm like the two old buzzards in the desert though.
The other strategy that I managed to get to work
once was to concentrate on military and industrial techs while building a standing army that I could afford, while also building a good-sized mob pool. I slowly, and I emphasize slowly, began creating a Greater Brazil in SA. If you move too quickly and create too much badboy, you're gonna have the UK, France, and the Netherlands jump on you like stink on manure. If you are decent at Victorian warfare, then go for it. Otherwise, be judicious on which provinces you annex into your empire, and satellite the rest.
Getting immigrants while playing as Brazil is more like icing on the cake. If you ain't gotta decent-tasting cake, no amount of icing is gonna make it better.