Brighton Beach was the destination for many ex-Soviet citizens, mostly Jewish, when a big wave of immigration from the USSR happened back in the 1970s. There's still plenty of them living down there, but mostly it's the senior citizens who still watch US based Russian language TV channels, read Russian papers published in the States and still speak poor English because they've been living among their own and are surrounded by Russian speaking businesses in the area.
Nowadays majority of Russians that arrived in NYC over the last twenty-thirty years live all over Brooklyn, Queens and Manhattan, to lesser degree in the Bronx. Back when I lived in Brooklyn, my place was in Bensonhurst, which used to be predominantly Italian, but now there are plenty of Russians, Chinese, etc.
So to answer your question Brighton Beach still have plenty of people speaking Russian, but most modern immigrants from the former USSR don't live there and don't visit the place often. If you're an immigrant with Russian being your first language and you want to adapt and assimilate in the US, Brighton Beach is the last place you'd want to live in.