The furnace burner area appears to be 18" above the garage floor, but it should be checked.
As for the oil tank in a garage…
Subsection 8.3.1 of NFPA 31 requires the fill pipe to terminate outside the building in which the tank is installed. Tanks located in garage bays shall be provided with adequate protection from vehicular traffic.
The tank should be placed in an area where it is unlikely to be adversely
affected by normal household activities.
Tanks should be installed on the lowest floor of the building. The exception to this would be if the tank is installed in an attached garage that is not the lowest floor.
The oil supply lines should be protected from mechanical damage.
Inside oil tank(s) shall be located not less than 1.5 m (5 feet) from any fuel-fired appliance.