That is too open ended to know. There are many different levels in blue belt. There's a huge difference in a blue belt with no stripes, and a blue belt with 4 stripes. It will also vary from school to school. Some give out blue belts like candy, and some you must be very skilled and attend way more than 2 classes per week, to include drilling only, and live rolling. I've met blue belts that can tap purples, browns, and blacks. And remember, it's a new age of jiu jitsu where kids begin training very young and may be blue belt between 16-20 years old but their overall time training is way more than an adult who's been training 1-2 years and received a blue belt. You can feel the difference rolling with those kids who have many years of training.

So, could a blue belt beat Mike Tyson? It's possible, yes, or they may also get their teeth knocked in. Even long term black belts can fall prey to great striking. Once it goes to the ground grappling has an advantage, but striking on the ground changes jiu jitsu, as we see in mma and combat jiu jitsu.