Once the H1 petition is approved, depending on the start date which is october, can he file for B1 extension to stay for an additional time so that he will be here in US until the start date?
Yes, the employer can file for him while he is still in the US. Yes, he can file for an extension but is unlikely to receive one.
The answer provided is general in nature and should not be construed as legal advice as not all facts are know by the attorney, nor does the answering of this question create an attorney client relationship.
Sorry, for practical reasons this won't work.
Although they can file in April, he can't get an H-1B before October 1, 2014 ... far longer than his B-1 is currently valid ... and, it will be unwise to try to extend the B-1.
He should enjoy his vacation and go home to get the H-1B ... returning in October.
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