Can I replace flour in a soup recipe with a 1 to 1 gluten free flour?

I have celiac disease and must eat a gluten free diet.

I saw a recipe for creamy chicken and mushroom soup, and it looked delicious! However, it called for 1/4 cup all-purpose flour. Would it be better to use a 1 for 1 gluten free all purpose flour or use corn starch instead? If I used corn starch instead, I'm assuming I wouldn't use 1/4 cup....but how much SHOULD I use?