I’ve never heard of a t90 with a turbine. Newer tanks (since 2004) are equipped with a new diesel, wich, among other things features a turbocompressor, but there are no serial production T90s with a gas turbine. Maybe some prototypes? I don’t know.
A russian gas turbine tank is T80 (first deployed in 1976). Well, I never studied the question, but both T90 and T80 are both on active duty. Turbine is more expensive, but looks generally beter from the technical characteristics point of view. However, I have to say that for Russian tanks the engine in general is a traditional weak spot, Russian tank engines are (as a very general rule) worse than European, American and Israeli ones. The T90 older diesels, for example were shutting down at +40 degrees outside temperature, unless additionaly cooled (Nobody cares in Russia, but the Indians were quite shocked as they learned it after buying the tanks :) I’ve heard tankers call that engine “total shit”. About the new one, I’ve no information, looks like it’s much better.