The Shoshone (Autocracy) have one point of influence on you, which means they are one influence category (unknown, exotic, popular, etc.) over you as compared to you over them (not surprising, since they are generating the most tourism). To confirm, go to the last screen and check your influence over them, and then check their influence over you. That screen will also show what tourism he has vs. you and you vs. him. Note that tourism back and forth can be modified by various in-game tools, so you can't just look at his 70 base tourism and your 49 base tourism. For example, if you sold him open borders and he has a trade route running to you and a diplomat in your capital, he will have at least +59% tourism modifiers vs. you (+25% from borders, +25% from trade route, +25% from diplomat and -34% from differing ideology). On the other hand, if you have no modifiers and no diplomat in his capital, you will be at -34% modifier (different ideology). That combo would mean he would be sending you 111 tourism and you would be sending him only 32 tourism, which, obviously, is not likely to close the gap any time soon.
Best defense is a two-pronged approach -- generate more culture to prevent him from gaining further ground and generate more tourism (and tourism modifiers) over him to get to parity (e.g., if he is exotic on you but you are unknown to him, more culture will help keep him at exotic over you and more tourism will help you get to exotic on him).