No, there is no fixed percentage for Basic from CTC.
In the aviation industry in India, a line pilot earns almost 50 to 100 times his basic pay! (A line pilot earns about 5 Lacs per month, but his basic pay is Rs 5000 - the rest is all allowances).
In most reputed companies, the Basic scale is linked to the position the employee is recruited for - e.g., the Basic Pay for an Asst Manager is the same, irrespective of the department. However, the CTC differs based on the job performed by the individual. For example, a technical manager may receive a higher (or lower) CTC compared to a marketing manager due to PLI, etc. But the pecking order for both (Manager designation) will be the same as per the company's hierarchy and promotions.
Regards,
Rajusiachen