Jim's claim about Gospel dating: Mark was written 40 years after Jesus at the earliest, and John was written 100+ years after Mark — implying John is 170 AD or later

Jim states the earliest Gospel (Mark) is no earlier than 40 years after Jesus' death (70 AD), and that there is a span of 100+ years between Mark and the last Gospel (John), placing John at 170 AD or later. Mike says this is wrong on both counts.