Well It seems that the default install of Gnome Terminal in Version 3.14.2 doesn’t play nicely with Irssi. If you have multiple channels open, you’re unable to ALT-1 or ALT-2 to get to each channel.
It’s an easy fix, open a terminal, and from the top of the screen right click terminal and click preferences
Scroll down until you see the TABS section
Double Click where it says ALT-1
It’ll ask for a new modofier, Press the backstpace key, and it’ll change it to disabled.