I'm not quite as pessimistic as the others who've replied so far. I think if someone knew Russian well, and could play around in Photoshop with sharpness, contrast, definition, etc, then they'd be able to make out 90% of what is says.
The reason I say that isn't judt wild optimism, but the way the brain sees and reads. If that was in English, i'm confident I could make out the words because we don't need to be able to see every detail of each individual letter - our reading works on the general shape of words, and there is enough detail in the picture to get that. For some words you'll find different adjustments in Photoshop will help different words, but without knowing what the words should look like (because I don't know the language) it's impossible to manipulate the image and know whether i've made the critical details better or worse.
So sorry that doesn't help directly, but i think you need to direct your question to people fluent in Russian with a little bit of photo editing background, rather than people with just the photo editing experience.
David