Orlando area cabs are $2.00 for the first 2/7 mile and then $0.25 per 1/7. This makes it $3.25 for the first mile and $1.75 each additional.
I live two miles North of Universal's entrance and 15.5 miles from the Epcot parking lot (passing Universal on the way). Therefore it would be 13.5 miles from the Epcot lot entrance to the Universal entrance. Based on this, you should figure in the $30 each way range, plus tip.
Depending on how long you are staying, how you will get from the airport to the hotel and back, and what else you plan, you might want to consider renting a car.