Satan believes he has a freewill.
Satan not only believes he has freewill, he does have it. He makes choices everyday. His choices are to fight against God. He didn't always do that, according to general Christian theology. He was once Lucifer and had a high position in the Kingdom of God and serve God from there. And then he made a choice that cause his fall. He could choose to turn back and serve God at this point, but he won't. And even you and I know he won't. He just has gotten so much into his pride that he is not going to. God certainly knows he won't, and God even had written down what is going to happen to Satan because he won't, but even that doesn't mean he doesn't have the choice to repent, it only means he won't.
Jn 3:16 For God so love the world, that He gave His only begotten Son, that whoever believes in Him shall not perish, but have eternal life.
Now Satan is a "whoever" and is even call prince of the air, so he is of this world. This verse, if it is true and we do believe that right, means that even Satan could choose to believe (and it is worth noting that the Greek word for believe used here is often translated 'trusts') or trust in Jesus Christ so that he saved. However Satan is not going to come underneath Jesus Christ and puts his trust in Jesus Christ as his Lord. We can all see that Satan is not going to change, but that does not mean he does have the God given ability to do so. In fact it was that God given ability that caused his to change from Lucifer (who worshiped God) to Satan ( who hates God).
And we see that same thing in people, and even ourselves if we chance to consider ourselves. WE don't want to make Jesus Christ our Lord, and put our trust in Him. If we do, we will get up every morning and choose to seeking Him for instructions, advice, counsel, wisdom, understanding, and more. Some people do that though not perfectly. I do that, but not perfectly. God knows that too, and has forgiveness of my sin, which is always a result of not seeking Jesus enough. But when I do He talks to me and I hear Him. He asked me to start a new thread about knowing Him. He specifically told me to do that, so I am going to. But that instruction came from seeking His voice and what He personally had to tell me. We can choose to seek Him or not. And the fact that He knows how we are and act even so that He knows and made plans that included all of us (even Satan who will not repent) is irrelevant to our God given ability to make a choice.
There is one difference between Satan and us. We have hope! Satan knows that because it is written down, he is not going to choose God. God can not be wrong. But you and I have the hope that we can be. That hope makes it a lot easier for us to turn back to God, but you still need to turn back and talk to Him.
The one big problem I see with some that preach predestination, (and from what I have read I don't believe John Calvin had this problem) is that predestination had sometime become an excuse for not turning back to God. Predestination should lead us to a God so great that He knows how we are and even how we would be, before the beginning of time. I believe that was what John Calvin was trying to point out. But sometimes predestination has become an excuse to not seek God or to discourage others from telling others to seek God. Now that is from Satan.