Almost every metric in what passes for economics these days needs to come with huge red flags and blazing bullhorns. Russia has the sixth largest economy in the world if you’re adjusting GDP by purchasing power, almost twice the size of Italy. But the truth is that, for reasons I explained in this forum earlier, GDP is an absolutely terrible metric of productivity or living standards. It should never be used to assess economic scale (ie the "size" of a country's economy). The fundamental problem with doing so is that economists aggregate through prices, which are unstable units of measurement, and thus they are forced to adjust for inflation and keep prices "constant" by picking an arbitrary point in time. This basic problem impacts even the fancy chain-weighted methods introduced by the Bureau of Economic Analysis in the 1990s. That's why the chain-weighted "real" GDP of the US in 2014 was $16 trillion if you're using 2009 prices as a reference and $17 trillion if you're using 2012 prices as a reference. That's a $1 trillion difference for reference markers that are only three years apart. What's the real number, you may ask? There isn't one. That's the point. Depending on how you decide to aggregate, you can come up with thousands and potentially millions of different GDP figures for the same country in the same year.Russia doesn't have an industrial base that is geared towards becoming high-income. Putin has consciously steered the country towards "maximum resilience" for almost a full decade now, trying to derisk the economy and creating "Fortress Russia". The price paid was slow growth in exchange for building a country that is (almost) sanctions proof.
That gives Russia tremendous survivability, but it ensures that it will remain stuck in the slow lane for the foreseeable future. China can help somewhat, but it is unrealistic to expect every single private Chinese firm to sacrifice the much more lucrative Western markets for a country whose economy is smaller than Italy's. It will be a balancing act for Beijing, and Russia will have to accept that it won't get everything it wants from China as part of that balancing act.
A more reliable and stable metric of economic scale is energy consumption. It doesn't have the aggregation problems that financial metrics do. In 2020, Russia used about 28 exajoules of energy, the fourth highest in the world, and almost three and a half times more than France (link below). Energy consumption is by far the best measure of national power, because it gets to core issues like what countries can actually do with the resources they have (instead of how those resources are priced and financialized for profit).