How did the dictionary influence the English language?

The 'invention' of the Dictionary has had two main influences:-

1.
The Dictionary has standardised spellings. Before dictionaries, some people kept lists of words. But in different parts of the country the spellings were often quite different, being influenced by local accents, or local spellings. For most people, they knew how to 'say' what they wanted to communicate, but they rarely had to 'write' anything! So when it came to writing, many just made up the spelling as they saw fit!

Even William Shakespeare's name was spelled/spelt several different ways!!! (See 'Related links' below)
Of course, the word 'Shakespeare' is a 'proper noun' and therefore is unlikely to be found in a standard dictionary. Even so, it is a good example of the significant variations in spelling that were common before Dictionaries began to be published and used as standard reference works.

2.
Dictionaries have made people more aware of language (and the meanings of language), and provided greater opportunity for people to increase their personal vocabularies.
The result is that, with good use of dictionaries, we are often better equipped to express ourselves because we have a wider range of words at our command, and we can then select those that best match the idea we want to express. And even if we occasionally use an obscure or abstruse word, the other person can always look it up ... in a Dictionary!