In Jedi Survivor, will Cal be able to use a gun?

It looks like in the trailer he might lose his lightsaber due to some sith (darth revan?)

so he might have to use a gun until he makes another one

Yes there will be multiple stances that Cal can do. We now from an interview (here) that we at least get the following stances

• Single lightsaber
• Dual wielding lightsaber
• Lightsaber with blaster
• Heavy stance (like Kylo Ren)

So yes we will be able to use a blaster!