This is a common statement by those who haven't read theory, especially among the Western Left, but this isn't true in any capacity. Billionaires are regularly executed in the PRC, the fact that the PRC has a private sector doesn't mean it has shifted away from Marxism-Leninism. The entire reason Marx predicted Socialism, ie Public Ownership and Central Planning, to overtake Capitalism is because markets naturally prepare the foundations for Socialism. Competition forces more and more companies to consolidate and grow, develop their own infrastructure for planning, which can be siezed and used by the public.

Question 17 : Will it be possible to abolish private property at one stroke?

Answer : No, no more than the existing productive forces can at one stroke be multiplied to the extent necessary for the creation of a communal society. Hence, the proletarian revolution, which in all probability is approaching, will be able gradually to transform existing society and abolish private property only when the necessary means of production have been created in sufficient quantity.

-Engels, The Principles of Communism

Half the economy of the PRC is in the Public Sector, and another almost tenth is in the cooperative sector. The Private Sector covers mostly light industry that depends on Publicly Owned industries like steel and public infrastructure. As Capital consolidates in the Markets, the CPC increases ownership. I recommend reading Socialism Developed China, Not Capitalism. Markets are more efficient at lower levels of development, and Public Ownership and Planning is more efficient at higher levels of development.

If you want to learn more about Marxism, I made an introductory Marxist reading list.