Is it a redox reaction if the oxidation state of the element has changed only in one of the products?
One sulphuric acid is used to form sodium sulphate and the other one is used for oxidizing. 
So you have a reduction:

$\ce{4H+ + SO4^2- +2e- -&gt; SO2 + 2H2O}$

and an oxidation:

$\ce{2Br- -&gt; Br2 +2e^-}$

The sodium sulphate is formed with:

$\ce{H2SO4 + 2NaBr -&gt; Na2SO4 + 2HBr}$

This last one is not a redox reaction.