I'm also in contact with a few guys in Porto Alegre...
They say the sauna tends to have less people (both boys and clients) in January/February, as people tend to want to go to the beach instead...
Sauna numbers start to increase in March, after carnival, when the weather begins to worsen and people return from the beach...
One guy in Mezzaninu, told me he would earn 2000 R$ per month (doing about 3-4 nights per week)
...and if he did a full time job in a mobile phone shop, he'd earn 1800 R$ per month