Hi,
There are 7 10th Dan players in JKA history. And, currently 4 players are alive.
- Mr. Issei Fujiwara, the first president of JKA, died in 1994
- Mr. Kazumitsu Takada, former vice president of JKA, died
- Mr. Yasutaro Arai, died in 2010
- Mr. Shizuo Tobari, former vice president of JKA
- Mr. Kinjiro Nomura, former president of JKA
- Mr. Yoshio Kanai, previous president of JKA
- Mr. Teruki Maruishi, current president of JKA
Basically, 10th Dan is given to JKA president or equivalent position today. And, 9th Dan is given to JKA vice president or equivalent position.
I am not sure how many 9th dan players are. But, I think there are about 10 or less.
7-8 Dan are currentry honorable degree. As Void said, they used to be able to get 7-8 Dan by doing tricks till 1991.
So, there are more 7-8 Dan players than 9-10 Dan. I think there are 20-30 7-8 Dan players are alive today.
In most cases, 7th dan is given to JKA officer after retirement of competitor. I am just a JKA trainer and still active competitor

I will share if I can get more confident information.
Thanks.