Well the 747 is pretty old-tech by today's airliner standards ( mockingly called a gas-guzzler ) but a 747-400 burns roughly 9,600 to 11,500kg of fuel per hour in the cruise per public-domain figures.

If we round the latter to 12,000 per hour and convert to litres at a density of 1.23 for kerosene, that's 43 litres per passenger for a British Airways -400 with 345 seats, which is fairly low density due to a large number of suites and business seats:

https://www.seatguru.com/airlines/British_Airways/British_Ai...

That 43 litres propels that passenger 510 nautical miles in one hour, 945km. 22km per litre.

Now, an Air Canada 777-300ER which is a generation on from the 747-400 burns about 8,500kg per hour with 458 passengers... And an A350-1000 should beat that by about 15% when it enters service.

The efficiency of even semi-modern airliners is remarkable.