Oh. I might get my betta tomorrow...maybe, maybe not.
I would say not
First, your goldfish:
-are in a tank way too small for them. The first goldfish needs 20 gallons and 10 gallons for any additional, I can't tell from the pic how many you have in there but for 2 you would need at least a 30 gal and for 3 at leat a 40 gal.
-I'm glad you're getting a bigger tank. That would probably need to be for the goldfish
-how are you caring for the goldfish now? Do you do water changes? how often? does the tank have a filter?
For the Betta (or any other new fish):
-don't even think about getting one until your tank is cycled. You'll need a heater and a good filter too, and if your tank is <5 gals it might be tough to put those things in, but they are needed. If you can return the smaller tank and save up for a bigger one that would be best.
-if you listen to nothing else I say at least cycle the empty tank first before you put anything else in! (
Read this on fishless cycling) Otherwise there's a good chance the new fish will get sick and diem (and you'll have to monitor the water closely with a test kit and change the water every day). It's best to take your time and do it right and provide a good home for your fish.
-also tetras and bettas may or may not get along (in a tank that small I would definitely say not) and the tetras need to be in a school of at least 6, plus they need a much larger swimming area. YOur small tank is even really too small for a betta, but if you are intent on putting it in there at least cycle it first, as I said. But no other fish than that. Otherwise it could make a good shrimp tank.