Can i use plugins that creates elementor widgets in wordpress theme


There is a plugin called Unlimited Elements for Elementor which lets you type your HTML/CSS/JS and generates an elementor widget for you that you can download as a .zip file, but you can only use it through that plugin.

The question is can I create elementor widgets that way and require that plugin in my WordPress theme to sell? will my theme be accepted?


Yes you can use Elementor page builder for your website hope there will be no problem.
Here you check about themeforest WordPress requirements


You can use external plugins. But, they should be free distributed as I know.