This is hard to say simply due to the large number of variables that exist. For example from where will the long-term migration? what are the incentives, how is the situation in the colony, how is race viewed there, etc.
Maybe more maybe less it all depends on the culture of the colony and its decisions long term.
And this will not happen, the region is very valuable for the other side to let go, especially in terms of resources. Even if the Huguenots are the majority in the colony, which is not something expected, they will fight for the region.
This is something that has always caught my attention, the tendency to imagine the colonization of Latin America by the French creating Haiti. I don't know if it's a lack of knowledge, little interest, or imposing the view of what happened in Haiti on the rest of America. Let's assume that the ethnic composition is similar to that of Otl (which is unlikely due to greater migration from France).
Rio de Janeiro: Whites: 46.5%; Pardos ( Mix people of white, black, and indigenous descent): 43.8%; Blacks: 8.8%; Yellow: 0.8%; Indigenous: 0.1%.
Minas Gerais: Whites: 47.2%; Pardos: 44.1%; Blacks: 7.9%; Yellow: 0.7%; Indigenous: 0.1%.
São Paulo: Whites: 58.8%; Pardos: 30.4%; Blacks: 8.3%; Yellow: 2.2%; Indigenous: 0.3%.
All of these states have a simple white majority unless you are considering mixed race as black. Then we have a simple black majority. In this case, this will depend on how race is seen in the colony and how interactions occur. For example, will the French Catholics mix with black people in the same way as the natives did or not?
You just don't know about South America, ok, that makes sense, it's a continent that a lot of people have little knowledge of. Well, malaria is a disease that spreads primarily in the Amazon due to its climate. Malaria is not one of the diseases that occurs in the southeast of Brazil or even in the northeast.
This is a map of malaria in Brazil and the world.
White Catholics will migrate to Minas Gerais, São Paulo, and Rio de Janeiro. Because these states are the heart of the country and the climate is good enough for Europe. The land is more secure and the central catholic government is at its strongest. Regarding land in Argentina, yes Catholics will migrate too, but unlike Huguenots who will probably want land far from the central government, they probably will go to the few major cities. At least until the 19th century with its mass migration. The Huguennt advance is generated by Catholic migration but will have to deal with the Spanish and aggressive tribes. Probably generating a culture similar to Otl (the Gauchos), basically a cowboy culture.
Another factor is what the composition of the population will be like during the gold rush. I would say she should go heavily towards the masculine side. So we will probably have a large mixed group. The question will be whether they will mix with blacks at the same rate as they mix with natives.