Yes a giant squid can kill a whale if the giant squid is much larger than the whale.
If the whale is much larger than the giant squid then the whale could kill the giant squid instead.
The Colossal Squid which is a very big giant squid could kill a whale easily.
The reason giant squids eyes are so big is to allow more light in and to allow the giant squid to see much better as well.
The giant squid eyes also help the squid determine ocean depths and giant squids are around 5 adult men people and the giant squids predators are also pretty large.
The largest Squid on record which was recorded by scientists is the Colossal Squid.
The Colossal Squid is as of now the largest species of Squid in the world and the largest Colossal Squid was 43 feet long and weight almost 1 ton which is 2,000 lbs.
The Colossal Squid is known as the Giant Squid.
Squids do have bones in their body.
Although the bones the squid has is not the same as a humans bones or other animals skeleton system.
The squid does have a skeletal system and skeleton in the form of a rod-like gladius or pen, made of chitin.
Squids are soft bodies creatures though.
If you cut into a squid you'll notice some bones but they will be very different than human or other animal bones.
I helped open up a squid in science class many years ago and remember the skeleton system in the squid so they do have a form of bones.
But they were not very large and were pretty brittle.
Some people also eat squid but I don't think I ever will.