However, if you're trying to manipulate the reading or review process in an unethical way, such as paying for only positive reviews, then it's not ethical. The purpose of getting someone to read your story should be to improve it, not to deceive others about its quality.
The best way to know is to keep an eye on the view count. If it goes up, that indicates someone has read your story. Another clue could be if you get direct messages or comments related to the story from someone.
You could start by sharing it on your social media platforms. For example, post a short teaser about your story on Facebook or Twitter with a link to where the full story can be read. Another way is to ask your friends and family directly. They are usually more likely to be interested in reading something you've written.
Getting someone to read your novel gives you fresh perspectives. They might notice plot holes or character inconsistencies that you missed. For example, if there's a sudden change in a character's behavior that doesn't seem logical, a new reader can point it out.
One option is to use freelance platforms. You can post a job on platforms like Fiverr or Upwork, stating that you're willing to pay for someone to read your story and provide feedback. Set a reasonable price based on the length and complexity of your story.