Sirius is 3 times as massive, so it has 3 times as much hydrogen too burn. On the other hand it is 21 times as luminous, so Sirius burns the fuel 21 times as fast.
Conclusion: Sirius will stay 3/21 = 1/7 times as long as the Sun a main sequence star, so about 10 billion/7 = 1.43 billion years.
