U6A and U6B are connected in parallel so that the output current is 2x.
R331 converts the outputs of UG(a,b) to a current.
So, about (15-0.6)/330 Amps flows into the base. That's 0.043 Amps
Hfe for a 2n2222 is probably around a 100. I didn't look it up.
The datasheet
https://www.electro-tech-online.com/custompdfs/2013/04/CD00003223-83285.pdf suggests 40. I'll still use 100. The end result is still mostly the same except the 4.3 A gets reduced by 40/100. A little over a factor of 2.
The 43 mA get's multiplied by about 100, so about 4.3 A CAN flow through the collector.
Ir's still way bigger than the transistor can handle, so the transistor will saturate and be fully turned on.