Can I take packaged and sealed pickled olives, olive oil and bottles of wine into China?

You can take all of them into CN. But you should declare the pickled olives at the customs.
If the alcohol volume of the wine is over 12%, you should also make a declaration for taking more than 1.5L. There is no specific amount limit for taking wine containing less than 12% alcohol, but you'd better not take too many bottles.
Remember to put these three items in checked luggage.