What does Russia have to gain while the US and China are engaging trade war?

Loss of focus, they hope

A chance to make money from China.

Trade War isn't what the USA has to worry about. Germany is the gasman for Europe, pumping Russian nat gas into EU nations, with Russia getting all the profits. All? Yup. All. Germany gets the "thrill" of having the "key" to the pumps. This is why Greece/Ireland/Portugal/Spain all threatened to not pay EU loan interest payments, then suddenly about-faced and paid them. Germany asked for the payments at the start of winter of course...

Russia found another large pool of gas and China has "graciously" offered to build Russia's rail infrastructure/etc, to make the East of the country as modern/accessible as the West of the country. "For free" also. Why would China/Russia care if rail traffic can get from one end of Russia to Asia? Hmmm... What do you want to bet China see's itself as a "Germany" selling Russian gas to Asia? Goodbye American influence.