Might be wrong about the numbers or statements. We hear of some communities that still speak French here and there in Louisiana, but it's really "quiet" compared to Quebec, whose independence movement is fairly well-known. Quebec is even considered a separate nation within Canada, added French as their official language
Obviously, French settlers would have constituted a much smaller proportion of the US population than in Canada, but still the disparity seems pretty stark. Were the French in USA treated worse/better? Was it because USA was/is a much more popular destination for migrants, so their identity got muddled?
I can't provide a detailed top level answer about modern political outcomes in Louisiana and Quebec, but I take issue with your central assumption that French settlers in Louisiana did not have have a "particularly strong influence or separate identity in USA." Rather, from what I understand from the scholarship, French settlers had an overwhelming influence on the culture and politics of the southern half of Louisiana right up until the 20th century.
Although a majority of all Louisianans were English speakers by the middle 19th century, sharp geographic lines separated the English-speaking North from the French-speaking South deep into the 20th century. English-speaking farmers (oftentimes with their enslaved human property) moved into the lightly-settled northern counties in the decades up to the Civil War, whereas the French population maintained their control of the south, including the two major cities Baton Rouge and New Orleans. While these cities would be predominately English-speaking by the end of the 19th century, French remained an important language in many urban neighborhoods and French-speaking elites, including creoles of color, had an important local influence on culture and politics.
Outside the cities, Lawrence E. Eastville argues that French remained the dominant language in the southern counties decades after WW2. Until the 70s, French was not simply a heritage language spoken by bilingual Americans, but the dominant language of a multiethnic society which newcomers had to learn to socially advance. Rather than be assimilated into the larger population of English speakers, the community of French settlers exerted an influence over newcomers. English-speakers moving into French areas of Louisiana (or in some cases, imported against their will as slaves) in the 19th and 20th century were assimilated into Creole and Cajun populations, thus maintaining the north/south language divide.
The eventual shift from French to English in rural southern Louisiana didn't really begin until the 1920s, when unsympathetic Anglo-American politicians sought to make English the primary language of communication statewide. Unlike in Quebec, French-speakers did not have enough representation in their legislature to resist these policies. Increased enrollment in English-speaking schools, as well as migration of English-speaking white settlers into Louisiana and white supremacist efforts to reduce the standing of creole communities of color, slowly eradicated most usage of French in the cities and towns, leading to the present situation where less than 5% of Louisianans are daily French speakers.
There's always more to be said, but you may also find some answers about how Quebec preserved its cultural/linguistic identity in this post by u/enygma9753.