Will rust effect the integrity of this tank?

I would look at it pretty closely, if it's just surface rust then don't worry about it, if it looks like it's eating all the way through, then you'd have a problem. From the pic, it looks like it might be more than surface rust though

That look pretty bad especially if its mild steel and not stainless. Once steel starts rusting that bad its pitted and unless ground and treated, like cancer it will continue to rust under the glass expanding until it shatters the glass.

If the glass meets thickness requirements for its dimension, I would remove the steel and rebuild the tank. If not Id replace it with stainless or aluminum angle. You could also refinish and preserve the steel but it would be allot of work, more then its worth when you can buy angle aluminum at Lowe's and cut it with a hack-saw.