There are a thousand routes to an airline job and everyone you all will tell you to do it a different way. Most licences can be converted, so for example you can get an FAA (American) PPL and convert it to EASA or vice versa. There are many good schools in both sides of the pond and all over the world. You can go modular or integrated depending on whether you want to pay £40k or £100k for the same licence. Basically you need the licence for where you want to fly if you're flying professionally. So EASA for Europe, FAA for the US, CASA for Australia etc.
Under the EASA modular system you start with a PPL, then get a night rating, ATPL exams, multi engine rating, instrument rating and CPL. The initial PPL can be any PPL from any country, so I usually recommend an FAA PPL for a few reasons: it's usually cheaper because GA is 100 times bigger in the US. The weather is usually better which means you can get your licence in a month. It includes night privileges as standard, and it's relatively cheap to add an IR which can be converted to EASA cheaply. Plus from a young man's point of view it's an adventure. Some people take 6-12 months to get a PPL in the UK because so many days are lost to poor weather and everyone wants to fly on the good days.
The best price of advice you can give is to get an EASA class one medical. All professional pilots need one and it's vital to make sure he can hold one before doing any flight training, as there are quite a few disqualifying conditions. Then start a PPL course somewhere. By the time he has a PPL he'll know what he needs to do.