I agree that spoken language influences text language, because say if you’re speaking to someone and you are being sarcastic to them, you could do the same thing by texting and send a sarcastic smiley face.
When you are speaking to someone you could be shouting at them and to show that when you’re texting you could be using capital letters to show you’re being serious or just use explanation marks.
The only difference in speaking and texting is that in speaking you use you’re voice to speak, but texting you don’t use you’re voice.
Example of texting: yo
Hi 
(smile).
Wuu2 hun 
(wink, and wuu2 means what you up to).
Nm bbe u (nm means nothing, bbe means babe).
React!