Whether an employee skills and his/her performance is based on his/her "English proficiency" ?

Whatever the job requires and forms a support and support cannot stand in my way, and the English language is very important in all professions and jobs

It is undeniable that language proficiency plays an  important role in determining employee skills. Nevertheless, it is not the sole criterion for judgement. An employee can have excellent language skills but lack technical efficiency, or find it challenging to maintain customer relations. As far as I am concerned, a smart employee knows how to identify weaknesses and sets improvement as a goal. For instance, an agent with promising interpersonal skills and language problems can search for means to make language learning an easier task. Presently, finances are less of an issue. What is more, even if finances turn out to be a real hindrance, I think companies do have a say in this respect. A functional and valuable company ought to make sure neither profile is neglected. Henceforth, for those who lack the skills necessary to thrive in a given position, trainings can be provided. The same goes for candidates with language problems. 

Yes it accounts more than 50%, further indicators can be checked

Employee skills based on involvement & how sound knowledge in his work.

In the modern world there is an always greater need for effective communication, a global market needs fast transactions which can be achieved only by a proper communication. English has a particularity, hardly to be found in other languages, being capable to fit any communication easely mutating to better fit our needs(see the globish English phenomenon or the always more important computer English) .

Not always , The industries has shown people from Nepal, Philipines , Chinese don't communication much but they are very honest and hardworker 

Yes agread at 60%; because doesn't fit this do not cover technical skills. 

if a person gets hesitation any where then remains back therefore he ca not submit thing which je want to submit

It is not required for employees skills and his performance to be based on his English Proficiency. Depends on the place he is working and work environment is placed with.

Language is important in business in order to well communicate, however proficiency in English is a must

English language the importance for anything science