Hello,
Since you've been together for 6 years I am assuming you are living together. You will have to get married first before your BF has a chance of getting reinstated or he will have to move out and maybe even then he won't get reinstated if he still dates you.
If his family doesn't talk to him now, there is a big chance that you will be treated like a second class by his family since you aren't a witness and you won't become one in the future. If you get married, he gets reinstated and then he fades, the family will blame YOU for his "weak spirituality." They will put pressure on him and you will be the cause of his spiritual problems and family problems.
If his family doesn't talk to him now, he may want to count his loss and forget about them and the cult as going back doesn't guarantee a better relationship with his family if he plans to fade after being reinstated.
If he plans on going back and continue going through the motions by going to all the meetings and doing what they require of him for a long time to satisfy his family, your "happy" life together may end up being not so happy.
Also, you need to know for a fact he doesn't believe any of it. You have to have a deep discussion with him about his believes because if he believes some of it deep inside, when he goes back those beliefs may resurface and you will be stuck married to a person you haven't met yet. If he really believes any of JW crap and wants to go back, you may want to put of marrying him and may want to reconsider your future.
Also, you going to the meetings now will not help him get reinstated until he's married to you, otherwise it will delay his reinstatement if the elders know he's living with you or even going out with you.
These are just general observations about JW/non-JW marriages, not a rule. Some marriages work between JWs and non-JWs but those are few and regrets are many. I wish you all the best and hope you discuss all aspects of his beliefs before you marry him while he plans to get reinstated.