Can you place a male betta fish in the same tank as a turtle?

I just bought a male betta fish and my birthday is coming up in the next month. I have always been hinting that I want a turtle because I love turtles. My boyfriend said he wants to buy me one for my b-day but my mom won't let me have one unless I can take good care of it (which I will!) and she wants to know if the two aquatic animals can live together maybe in the same tank. Can they? And if they can, what size/gallon tank will I need? Will they steal each other's food? Will the turtle eat the betta? Please Help! Thanks :)