To some extent SSC CGL preparation may help you in SBI Clerk preparation. Definitely, while preparing there are some of the common topics which are there in both the exams.
But, the level of both the exams are different. So, it depends on your preparation that how much level of the paper you can attempt. The level of the reasoning is quite easy in SSC CGL exam which is not the case in SBI clerk.
Also, the General Knowledge is different in both the exams. So, the level of the exam is different and it totally depends on you.
Reasoning is time consuming in SBI clerk so you have to practice more for that. So, focus on the Reasoning and General awareness for more to crack the SBI Clerk exam.
All the best!!!!