In my humble opinion, which others are welcome to oppose, Vios/yaris will not be a big hit in pakistan. It looks like it was designed by a child while the corolla is quite handsome in comparison, not to mention a better car overall, plus Gli resale is also bulletproof. And let's not forget that no one knows how long you'll have to wait for yaris to launch and then be delivered to you whereas corolla currently has short delivery period with free registration.
Keeping all this in mind, I'd spend some extra cash and get a gli now.
The areas where yaris fares better are better power, compact size and better fuel efficiency. If in your view, these pros outweigh the cons mentioned above, wait for yaris.