Wouldnt know the figures but the A340 is relatively popular with airlines. They are one of the safer airliners on our Earth. The 777 would be more superior in technical advances as the airliner is only around 6 or 7 years old.
AS for the 500 and 600 variants. The 600 series is very successful for a 2 year old with planes for:
Emirates (on order)
China Eastern Airlines
Lufthansa
South African Airlines
Virgin Atlantic just to name a few. The 500 series isnt quite so popular as of yet with only a handful of airlines operating them:
Emirates
Qatar Airlines
Singapore Airlines( thats all i know off the top of my head) I am sure as time takes its course there will be more orders.
Dont know about replacements of the A300 and A310. Off the topic…..I love the A340.