I'll agree with KevinB.
While Gore claims that the pores in Gore-Tex laminate are not able to be clogged as they're too small for material to enter the pores themselves, however over time foot powder, dirt, body oils etc. will accumulate on top of the gore-tex layer, thus "clogging" it essentially.
Wash your boots a couple times a year and you'll be ok. Also, I'd recommend not putting the foot powder into the boot itself, but rather apply it to your feet and the inside of your socks.