Depends what you mean.
The Russian military appears to be pretty shit at operating and maintaining anything more complex than a playing card. If their conventional missiles have - as some of the long range land attack and anti-ship missiles do - a failure rate of up to 60%, and their fast jets have an availability/serviceability rate of 30% (USAF is on about 85%), then asking what the reliability rate of the most complex systems they have is, and being a bit cynical about whether it matches the rhetoric, is quite legitimate.
That doesn't mean that even a 10% reliability rate for their nukes (while fucking hilarious) makes a nuclear exchange against them winnable/survivable.
Personally I think it's likely to be much higher than that, not least because I think their nukes, particularly the big, long range strategic nukes are likely to be where they concentrate their technical, human - and financial - resources.
Even if it were true, the 400 warheads thing, and spread evenly over the whole range of tactical and strategic warheads and launch platforms, and then spread over Europe and the US, it would probably end agriculture in Europe, there'd be no clean water for the next 10,000 years, and it would immediately kill perhaps 100 million people.
Doesn't stop them being shit though...