Considering the country was officially atheist until 20 years ago, I say praise God even if it's "only" 50 percent. And even if only 4% observe the faith daily, that's some 5.7 million people—about 7 times the total number of Orthodox in the US, pious or otherwise. 5.7 million pious Orthodox will have an impact in the long term.
Personally I think the 50-70% discrepancy is between those who are baptized Orthodox and those who self-identify as Orthodox. I could see having a 20% difference there.