If you win millions of dollars, your immigration status likely is not as much of an issue now as before the winning. That is, even if you were deported from the US, you would still have a lot of money on which to live. Persons with money can live comfortably practically anywhere in the world. Persons with money likely can live even better outside the US since the cost of living in many places would be less.
As far as I know, being in lawful immigration status is not a requirement to claim the proceeds of lottery winnings anywhere in the US. The taxes that are withheld from your winning may be higher if you cannot provide a tax ID. However, there are ways to file your tax returns to reclaim the extra taxes paid.
There likely is no reason to "give to friend who is citizen for 50%-50% deal" unless you want to give money to that friend anyway.
Depending on why your are "illegal", having millions of dollars may give you more options to legalize your immigration status.
What you should do is put the winning lottery ticket in a safe place and start interviewing professionals (attorneys, money managers, etc.) to get help on what you should do with the money and how you can fix your immigration status.
Not an immigration question.
(213) 394-4554 x0 Mr. Shusterman is a former INS Trial Attorney (1976-82) with over 35 years of immigration experience. His response to your question is general in nature, as not all the facts are known to him. You should retain an attorney experienced in immigration law to review all the facts in your case in order to receive advice specific to your case. Mr. Shusterman's statement above does not create an attorney/client relationship.
This is not an immigration question.
PROFESSOR OF IMMIGRATION LAW for over 10 years -- This blog posting is offered for informational purposes only. It does not constitute an attorney-client relationship. Also, keep in mind that this is an INTERNET BLOG. You should not rely on anything you read here to make decisions which impact on your life. Meet with an attorney, via Skype, or in person, to obtain competent personal and professional guidance.
I agree with my colleagues this is not an immigration question. If yo believe you may have some immigration issues stemming from the lottery winnings you should set a consultation with an immigration attorney to discuss your concerns.