I'm writing a persuasive paragraph on how the english language has gotten worse over the years using evidence from George Orwell's essay and current events. In my topic sentence do I state what I'm going to prove or only state the main idea?

Only a paragraph?

The topic sentence of a paragraph is the main idea or claim, and the other sentences in that paragraph are to explain and support why that sentence is true.

http://grammar.ccc.commnet.edu/grammar/paragraphs.htm#topic_sentences

I have these 2 sentences, but I am unsure of whether they clearly state that the english language has gotten worse:

"In a world where emojis, abbreviations and shortcuts have become the norm, the proper use of the English Language has become rarity. Over the years, the English Language is not something that has gotten better, and through his essay, “Politics and the English Language”, Orwell gave a deeper understanding of this problem."

Skip the first sentence, or use it as your conclusion. Use the second sentence as your topic sentence.

Don't capitalize the "l" on "language" except in the title of Orwell's essay.

When writing a persuasive paragraph, your topic sentence should capture the main idea of your argument rather than explicitly stating what you'll prove. It sets the tone for the paragraph and provides an overview of the point you'll be discussing. In this case, you could frame your topic sentence as follows:

"The English language has deteriorated over time due to factors evident in George Orwell's essay and supported by contemporary events."

This topic sentence conveys the main idea of your paragraph - the decline of the English language - while also indicating that it will be supported by evidence from Orwell's essay and present-day examples. Remember, your subsequent sentences should then expand upon your main idea and offer convincing evidence to support your argument.