Gift cards that are not a "gift" or that come as a consequence of performing for a company are considered the same as cash.  So, if he got $900, then he should have received a 1099-Misc.  Perks.com website even says they send one for over $600.

Because he did not, its hard to know how they classified the payment.  It's best to double check with them and get a replacement because what you enter should match what they sent to the IRS.  Also, if they did not list your income in Box 7, then you won't have to fill out a Schedule C and pay self-employment taxes.

If you received a 1099-MISC with the amount of the income in Box 7, Nonemployee Compensation, the person or company who issued the form did not consider you an employee*.  Because of this, they did not withhold any of your applicable social security or Medicare taxes. When this is the case, you generally will have to pay the full amount of these taxes (rather than just half) and include this on your federal income tax return (Schedule SE). When you report the income on a Schedule C, TaxSlayer will automatically calculate your self-employment taxes for you.  

When you receive a 1099-MISC with income in Box 7 that is for nonemployee compensation, the IRS requires that this income be reported on a Schedule C.

If you cannot reach them, then you can air on the side or overkill and list it in 1099-Misc Box 7 and do the Schedule C.  Your other option is to enter it under "less common income" and not do a Schedule C and see if the IRS has a problem with it and sends you a letter.