Will a viral respiratory infection cause tinnitus to get worse?

Possibly. Respiratory infections can cause the retention of fluid behind the ear drum. This can result in some hearing loss. This can increase the conspicuousness of tinnitus. Furthermore, this fluid can have toxins also possibly producing tinnitus when none was previously present.
Yes. Usually upper respiratory viral illnesses/infection cause inflammation of the nasal cavity and eustachian tube. This inflammation leads to swelling of the opening of the eustachian tube. While swollen, the eustachian tube doesn't open as often or as efficiently as it should. This absence of air can lead to worsening of tinnitus. It should improve when the cold resolves.

Related Questions

I had a viral respiratory infection, & now I have sinus pain. I also have painful swelling & a lump on the roof of my mouth. Can the sinus cause this?

No. Sinus infections do not usually produce a painful swelling on the roof of the mouth. The two problems may be related in that a viral infection may lead to both conditions. The painful lump should be investigated by an ENT doctor. Read more...