IFN-gamma is mainly produced by T cells and NKT cells. Therefore, my assumption is that you are referring to these cell types in vivo. A co-infection by a virus and bacteria at the same time, would increase the production of IFN-gamma. Further, cells can also produce a type I IFN and respond to this IFN.

I agree with Divaker Choubey

That co  infection  will  increase  the level  of IFN-gamma

I agree with you both Ishag and Divaker.

There will also be a lot of TNF produced!

Schildgen has put your thoughts in the right perspective.