Experts? 众人?? Who were the people?
This statement, from my point of view, disproves QF can be drunk rather than reinforce it.
如此喝将下去,醉也将他醉死了
So they're thinking that if QF keeps drinking he will be drunk and die from it. (it being the state of drunkenness)
殊不知乔峰却是多一分酒意,增一分精神力气
So it goes on to say that QF becomes more spirited the more he drinks. This means the people were wrong about QF dieing, and also wrong about him eventually becoming drunk.