CAN IT? Yes it can. It will NOT pass any safety inspection anywhere in North America. Welding on the wheel web is illegal and as mentioned dangerous. Why did it crack? Usually due to improper torquing of the wheel. A loose stud will cause it to flex starting the crack process. Cracks start due to flexing, not load or loading of a vehicle.
Bite the bullet and replace the wheel. As an aside, check the mate to it if it's on the back. chances are that it will also show signs of wear. A rust streak coming from a wheel nut is usually a sign of a loose lug nut.Aluminum wheels are more forgiving of loose lugs in that they will wear at the lug mating surface rather than cracking but even they will eventually.
Bob and Karen. Getting ready to begin a new journey!
1999 Southwind 35S on a F-53 chassis our first class A