Solution provided by a tax expert in the intuit community page (for Turbo Tax online):

It depends. I think I may have a solution for your dilemma. Before we begin though, delete your previous 1099-MISC entry into your program. To report.

1. Federal>wages and income
2. less common income>show more
3. Miscellaneous Income, 1099-A, 1099-C>start
4. Other reportable income>start
5. Answer yes to the first screen
6. Next will be a dialog box asking for the description of the income. Type in  1099-Misc for gambling winnings. Record the amount of income that is listed on the 1099-Misc.
7. After you make this entry and press continue. This will take you to a summary screen. Here select add another miscellaneous Income Item
8. Here you will first describe this as Gambling Losses that offset my Gambling winnings. You will enter this number as a negative number such as -xxxx.xx.  
9. Caution do not enter an amount of gambling losses in excess of your winnings. Also, if you entered gambling losses elsewhere in your return like from a W2G, be careful not to duplicate these losses against other losses you may have already claimed.