That depends entirely on whether your ESA is contributory or income related. If it is contributory then your partner's income/assets will not affect it, if your ESA is income-related, in part or in whole, your partner's income/assets must be declared and could reduce the amount of ESA you receive. I cannot tell you an exact figure as this also depends on whether you are entitled to any ESA 'premiums'.
Nothing on this board constitutes legal advice - always consult a professional about specific problems
Just to add to Mrs H's advice, if you are receiving Income Related ESA in part or in whole, then entitlement to payment for that ESA(IR) will cease if your partner work for 24 or more hours a week.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems