It is not. A lot of the Brazilian rainforest is used to grow soy. Well over 96% of soy from the Amazon region is fed to cattle, pigs and chickens around the world according to data from the UN Food and Agriculture Organization.
Livestock are fed soy because it helps them grow faster, fatter, and is cheaper than grass. If you want to protect forests that are being replaced for soy farms, you can consume less meat.
Furthermore, 97% of Brazilian soy is genetically modified, which is banned for human consumption in many countries and is rarely used to make tofu and soy milk in any case. [The Guardian]

Topic: FAQ – Environment