I have a sore thorat with a yellow blister can it be strep throat?

Possibly: A sore throat with a yellow blister type lesion could be strep, other bacteria, a viral infection, or tonsillolith (tonsil stone). Hard to say. If it hurts badly or doesn't go away in a couple of days, get it checked out.

Possibly: Depending on the location of the blister, it could be a viral infection or possibly streptococcus infection. The most appropriate way of determining this is with a proper throat culture or a so-called rapid strep test. If it is truly a fluid filled blister, my best bet is a viral infection of the herpes family of viruses. Blood blisters deep in the ear canal are notoriously of viral origin.

Possibly: It could be a strep throat or a sore throat due to a virus or other bacteria. The yellow blister is likely a tonsil cyst or a collection of infected debris in the tonsil crypt.