If I breath helium into a bubble gum bubble, the gum would fly away?

All the air above a point pushes down with the weight of the air. Whatever is below that point pushes up with an equal force, so nothing moves. If you have a volume of something denser than air, its weight pushes down with a greater force than the air beneath it, so it sinks with a force equal to the difference. If you have a volume of something less dense than air then the difference in pressure pushes up and it floats, depending on the weight of the bubble. So you weigh your gum and add the weight of your spit and estimate the volume of the bubble versus the weight of the same volume of air and maybe you can handle all that arithmetic. I wouldn't. I would just guess.

A cubic meter of air weighs about 1.3 kg and helium is about 0.138 times that, so a cubic meter of bubble might lift about 1.3 x (1 - 0.138) = 1.12 kg. It is up to you to figure out how big your bubble is and what it weighs without gas in it.

The answer to your question is "Yes, maybe, I dunno, what do you think?"