You can’t go current
If you stopped making payments 8 months ago, the account is already closed and charged-off. It sounds like its one step away from being sent to collection.
You do not have the option of bringing it current and making payments. At this point, they’re no longer interested in payments. They want to settle with a lump sum and write the account off.
Declining the offer can potentially damage your credit further. You’ll probably get sued, and you can find yourself with a judgment against you. Not good for you and for your credit. Accepting the offer can also spare you the “pleasure” of dealing with collection agencies.
Take the settlement. It’s a good deal. Keep that letter offering this settlement and pay with a USPS money order or cashier’s check.