Alfablue correctly links the state of the waterproofing to breathability.
In rain the outer layer must be waterproof so that beading occurs and the Gtex will then breathe, otherwise breathability is compromised by a soaking outer layer.
An older GTex can be made more breathable by washing it as per manufacturer's instructions before rewaterproofing with something like TX-10. Just ask at a good outdoor shop.
Jase